Steering control system and method

ABSTRACT

An electronic control system for a vehicle includes a plurality of input devices, a plurality of output devices, a communication network, and a plurality of interface modules. The plurality of input devices may include a first input device that provides information pertaining to an angular position of a first vehicle wheel. The plurality of output devices may include an actuator capable of adjusting one or both of the angular position of the first vehicle wheel or an angular position of a second vehicle wheel. The plurality of interface modules can be microprocessor based and can be interconnected to each other by way of the communication network. The plurality of interface modules may also be coupled to the plurality of input devices and to the plurality of output devices. The plurality of interface modules may include one or more interface modules that is coupled to the first input device and to the actuator. The electronic control system can be configured to control the angular position of one or both of the first and second vehicle wheels as a function of the information from the first input device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Prov. No. 60/449,797, filedFeb. 24, 2003, entitled “Steering Control System and Method” and to U.S.Prov. No. 60/388,451, filed Jun. 13, 2002, entitled “Control System andMethod for an Equipment Service Vehicle,” each of which is herebyexpressly incorporated by reference. This application is also acontinuation-in-part of U.S. Ser. No. 10/325,439, filed Dec. 20, 2002,entitled “Equipment Service Vehicle With Network-Assisted VehicleService and Repair,” pending, which (1) is a continuation-in-part ofU.S. Ser. No. 09/927,946, filed Aug. 10, 2001, entitled “MilitaryVehicle Having Cooperative Control Network With Distributed I/OInterfacing,” pending, which is a continuation-in-part of U.S. Ser. No.09/384,393, filed Aug. 27, 1999, entitled “Military Vehicle HavingCooperative Control Network With Distributed I/O Interfacing,” now U.S.Pat. No. 6,421,593, which is a continuation-in-part of U.S. Ser. No.09/364,690, filed Jul. 30, 1999, entitled “Firefighting Vehicle HavingCooperative Control Network With Distributed I/O Interfacing,”abandoned; (2) is a continuation-in-part of U.S. Ser. No. 09/500,506,filed Feb. 9, 2000, entitled “Equipment Service Vehicle Having On-BoardDiagnostic System,” now U.S. Pat. No. 6,553,290; (3) claims priority toU.S. Prov. No. 60/342,292, filed Dec. 21, 2001, entitled “VehicleControl and Monitoring System and Method;” (4) claims priority to U.S.Prov. No. 60/360,479, filed Feb. 28, 2002, entitled “Turret ControlSystem and Method for a Fire Fighting Vehicle;” and (5) claims priorityto U.S. Prov. No. 60/388,451, filed Jun. 13, 2002, entitled “ControlSystem and Method for an Equipment Service Vehicle;” all of which arehereby expressly incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to steering control systems and methods.In particular, the present invention relates to electronic controlsystems and methods of steering a vehicle.

All wheel steering systems are known in the art. Examples of all wheelsteer systems are described in U.S. Pat. Nos. 5,607,028, 5,417,299,5,217,083, and 5,111,901, all of which are entitled “All-Wheel SteeringSystem,” and are hereby incorporated by reference. Some known all-wheelsteering systems are purely mechanical, meaning that the rear wheelangle is determined by gears and gear ratios manually selected by thevehicle operator with the shift of a lever. Unfortunately, this type ofall wheel steering system adds considerable weight and complexity to themechanical subsystem of the vehicle. Other all-wheel steering systemsprovide rear wheel steering independent of the front wheel angle wherethe operator steers the rear wheels independently of the front wheels,the rear wheels being steered with a separate steering wheel, joy stickor potentiometer. This type of system is typically used on vehicles thatare steered by two operators: one operator steers the front wheels andone operator steers the rear wheels. Unfortunately, the use of twooperators has a number of disadvantages such as increasing the laborcosts associated with operating the vehicle. Electronically controlledsystems have also been employed.

All wheel steering systems are often used on larger vehicles such astrucks. It is desirable for these vehicles to be able to maneuver intosmall spaces in short periods of time. All-wheel steering provides greatbenefits in this regard because it provides a smaller minimum turningradius. All-wheel steering systems may also be used in other types ofvehicles.

All wheel steering systems, particularly those that are electronicallycontrolled, typically implement steering algorithms to control steeringof one or more sets of wheels. In order to provide flexibility in thetypes of steering algorithms that can be implemented, it is desirable toprovide all wheel steering systems with access to a variety of sourcesof vehicle data. It is also desirable in many instances to provide otherelectronic systems on-board the vehicle with access to data from thesteering control system. What is needed is a control system architecturethat provides an improved integration of the steering control systemwith other vehicle devices.

All-wheel steer systems typically have more modes of operation than astandard front wheel drive system. In order to allow a vehicle operatorto use an all-wheel steer system most effectively, it is desirable toprovide the operator with feedback regarding operation of the systemincluding vehicle diagnostics. What is needed is improved systems forproviding operator feedback in connection with a steering controlsystem.

It is typically necessary to periodically calibrate the steering systemof an all wheel steering vehicle. Often these systems are difficult tocalibrate and require that the operator to get underneath the truck.What is needed is a steering control system that it is easier tocalibrate.

Accordingly, there is an ongoing need for improvements to controlsystems and methods used in connection with such steering systems. Itshould be understood, however, that the techniques below extend to thoseembodiments which fall within the scope of the appended claims,regardless of whether they meet any of the above-mentioned needs.

SUMMARY OF THE INVENTION

In one embodiment, an electronic control system for a vehicle includes aplurality of input devices, a plurality of output devices, acommunication network, and a plurality of interface modules. Theplurality of input devices includes a first input device that providesinformation pertaining to an angular position of a first vehicle wheel.The plurality of output devices includes an actuator capable ofadjusting the angular position of the first vehicle wheel or an angularposition of a second vehicle wheel. The plurality of interface modulesare microprocessor based and can be interconnected to each other by wayof the communication network. The plurality of interface modules arealso coupled to the plurality of input devices and to the plurality ofoutput devices and include one or more interface modules that is coupledto the first input device and to the actuator. The electronic controlsystem is configured to control the angular position of one or both ofthe first and second vehicle wheels as a function of the informationfrom the first input device.

In another embodiment, an electronic control system for a vehicleincludes a plurality of input devices, a plurality of output devices, acommunication network, and a plurality of microprocessor based interfacemodules. The plurality of input devices includes a sensor that providesinformation pertaining to an angular position of a first vehicle wheel.The plurality of output devices includes an actuator capable ofadjusting an angular position of a second vehicle wheel. The pluralityof microprocessor based interface modules are interconnected to eachother by way of the communication network. The plurality of interfacemodules are also coupled to the plurality of input devices and to theplurality of output devices, and include one or more interface modulesthat is coupled to the sensor and to the actuator. The electroniccontrol system is configured to control the angular position of thesecond vehicle wheel as a function of the angular position of the firstvehicle wheel.

In another embodiment, an electronic control system for a vehicleincludes a sensor and an actuator. The sensor is configured to providedigital signals pertaining to an angular position of a first vehiclewheel. The actuator is capable of adjusting one or both of the angularposition of the first vehicle wheel or an angular position of a secondvehicle wheel. The electronic control system receives the digitalsignals from the sensor and controls the angular position of one or bothof the first and second vehicle wheels.

In another embodiment, a vehicle having an electronic control systemincludes a first set of vehicle wheels with a first wheel angle, asecond set of vehicle wheels with a second wheel angle, and a pluralityof modes for controlling the second wheel angle as a function of thefirst wheel angle. The plurality of modes include a first mode and asecond mode. The electronic control system is configured to receiveinput to change from a first mode to a second mode, and, in response tothe input, the electronic control unit is configured to operate in thefirst mode until at least one of the sets of vehicle wheels travelsthrough a straight-ahead position at which time the electronic controlunit changes to the second mode.

In another embodiment, a vehicle having an electronic control systemincludes a first set of vehicle wheels with a variable first wheelangle, a second set of vehicle wheels with a variable second wheelangle, and a lock configured to maintain the second set of vehiclewheels in a locked position. The electronic control system controls thesecond wheel angle as a function of information pertaining to a firstwheel angle. The locked position of the second set of vehicle wheels isinput into the electronic control system as a calibration point for astraight-ahead position of the second set of vehicle wheels.

In another embodiment, a vehicle having an electronic control systemincludes a first set of vehicle wheels with a variable first wheel angleand a second set of vehicle wheels with a second wheel angle. Theelectronic control system controls one or both of the first and secondwheel angles. The electronic control system is configured to log theposition of one or both of the first and second set of vehicle wheels.

In another embodiment, an electronic control system for a vehicleincludes a sensor, an actuator, and a graphical user interface. Thesensor provides information relating to an angular position of a firstset of vehicle wheels. The actuator is capable of adjusting an angularposition of a second set of vehicle wheels. The electronic controlsystem controls the angular position of the second set of vehicle wheelsas a function of the angular position of the first set of vehiclewheels. The graphical user interface displays calibration instructionsfor calibrating the straight-ahead position of the first and second setsof vehicle wheels.

In another embodiment, a system includes a vehicle and a vehicle wheelalignment system. The vehicle includes a first set of vehicle wheelswith a variable first wheel angle, a second set of vehicle wheels with avariable second wheel angle, and an electronic control system. Theelectronic control system controls the second wheel angle as a functionof information pertaining to the first wheel angle. The electroniccontrol system also receives input from the vehicle wheel alignmentsystem and uses the input to determine the straight-ahead position ofthe second set of vehicle wheels.

In another embodiment, a vehicle having an electronic control systemincludes a first set of vehicle wheels with a variable first wheelangle, a second set of vehicle wheels with a variable second wheelangle, and a graphical user interface. The graphical user interfaceincludes a representation of the vehicle including an image of the firstand second sets of vehicle wheels wherein the first and second wheelangle in the image change as the first and second wheel angle of thefirst and second sets of vehicle wheels change.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a fire truck having a control systemaccording to one embodiment of the present invention;

FIG. 2 is a block diagram of the control system of FIG. 1 showingselected aspects of the control system in greater detail;

FIG. 3 is a schematic view of a military vehicle having a control systemaccording to another embodiment of the present invention;

FIGS. 4-5 are block diagrams of the control system of FIG. 3 showingselected aspects of the control system in greater detail;

FIG. 6 is a diagram showing the memory contents of an exemplaryinterface module in greater detail;

FIG. 7 is truth table in which an output is controlled with anadditional layer of failure management for inputs with undeterminedstates;

FIG. 8 is an overview of a preferred variant vehicle system;

FIG. 9 is a block diagram of the control system of FIG. 3 showingselected aspects of the control system in greater detail;

FIG. 10 is an I/O status table of FIG. 9 shown in greater detail;

FIG. 11 is a flowchart describing the operation of the control system ofFIG. 9 in greater detail;

FIG. 12 is a data flow diagram describing data flow through an exemplaryinterface module during the process of FIG. 11;

FIG. 13 is a schematic diagram of an exemplary embodiment of an electrictraction vehicle providing an exemplary embodiment of an AC bus assemblycoupled to various modules on the vehicle;

FIG. 14 is a schematic diagram showing the vehicle of FIG. 13 being usedas a mobile electric power plant;

FIG. 15 is a schematic diagram showing selected aspects of a controlsystem of FIG. 13 in greater detail;

FIG. 16 is a flowchart showing the operation of a control system of FIG.13 in greater detail;

FIG. 17 is a schematic diagram showing auxiliary drive modules used inthe vehicle of FIG. 13;

FIG. 18 is a flowchart showing another aspect of the operation of acontrol system of FIG. 13 in greater detail;

FIG. 19A is a top plan view illustration of an exemplary embodiment of adifferential assembly coupled to an electric motor for driving at leasttwo wheels and supported by a suspension assembly, and FIG. 19B is anend view partial sectional view of an exemplary embodiment of anelectric traction vehicle support structure coupled to a suspensionassembly which suspends at least one wheel relative to the vehiclesupport structure;

FIGS. 20A-20B is a block diagram showing various configurations forconnecting interface modules to drive controllers in the electrictraction vehicle of FIG. 13;

FIG. 21 is a schematic block diagram illustrating various entitiesconnected to the Internet for the transmission of data indicative of anelectric traction vehicle;

FIG. 22 is a schematic view of a military vehicle having a diagnosticsystem according to one embodiment of the present invention;

FIG. 23 is a block diagram of the diagnostic system of FIG. 22 showingselected aspects of the diagnostic system in greater detail;

FIG. 24 is a menu displayed by a display of the diagnostic system ofFIG. 22 showing various services offered by the diagnostic system;

FIG. 25 is a flow chart showing the operation of the diagnostic systemof FIG. 22 to perform a diagnostic test procedure;

FIG. 26 is a schematic view of a firefighting vehicle having adiagnostic system in accordance with FIGS. 22-25;

FIG. 27 is a schematic view of a mixing vehicle having a diagnosticsystem in accordance with FIGS. 22-25;

FIG. 28 is a schematic view of a refuse handling vehicle having adiagnostic system in accordance with FIGS. 22-25;

FIG. 29 is a schematic view of a snow removal vehicle having adiagnostic system in accordance with FIGS. 22-25;

FIG. 30 is a schematic view of vehicle maintenance, monitoring, partsordering, readiness assessment, and deployment system according toanother embodiment of the present invention;

FIG. 31 is a flowchart showing the operation of an on-board vehiclecomputer system in the system of FIG. 30 during a parts orderingprocess;

FIG. 32 is a flowchart showing the operation of a maintenance centercomputer system in the system of FIG. 30 during a parts orderingprocess;

FIG. 33 is another flowchart showing the operation of an on-boardcomputer system in the system of FIG. 30 during a parts orderingprocess;

FIG. 34 is a flowchart showing the operation of a maintenance centercomputer system in the system of FIG. 30 during a readiness assessmentprocess;

FIG. 35 is a flowchart showing the operation of an on-board vehiclecomputer system in the system of FIG. 30 during a readiness assessment;

FIG. 36 is a flowchart showing the operation of the system of FIG. 30 todetect non-conformance to a predetermined route; and

FIGS. 37-47 are various examples of screen display for real time remotemonitoring of vehicle I/O status information; and

FIG. 48 is a block diagram showing a steering control system accordingto an embodiment of the present invention;

FIG. 49 is a block diagram showing selected aspects of the block diagramof FIG. 48 in greater detail;

FIG. 50 shows various modes of operation of the steering control systemof FIG. 48;

FIGS. 51A-51B is a deadband versus speed graph for the steering controlsystem of FIG. 48;

FIGS. 52-54 are screens of a graphical user interface for the steeringcontrol system of FIG. 48;

FIG. 55 is a flow chart showing a calibration operation for a vehiclehaving the control system of FIG. 48; and

FIG. 56 is a schematic diagram of an alternative alignment mechanism forthe steering control system of FIG. 48.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A. Fire Truck Control System

1. Architecture of Preferred Fire Truck Control System

Referring now to FIG. 1, a preferred embodiment of a fire truck 10having a control system 12 is illustrated. By way of overview, thecontrol system 12 comprises a central control unit 14, a plurality ofmicroprocessor-based interface modules 20 and 30, a plurality of inputdevices 40 and a plurality of output devices 50. The central controlunit 14 and the interface modules 20 and 30 are connected to each otherby a communication network 60.

More specifically, the central control unit 14 is a microprocessor-baseddevice and includes a microprocessor 15 that executes a control program16 (see FIG. 2) stored in memory of the central control unit 14. Ingeneral, the control unit 14 executes the program to collect and storeinput status information from the input devices 40, and to control theoutput devices 50 based on the collected status information. The controlprogram may implement an interlock system, a load manager, and a loadsequencer. As described below, the central control unit 14 is preferablynot connected to the I/O devices 40 and 50 directly but rather onlyindirectly by way of the interface modules 20 and 30, thereby enablingdistributed data collection and power distribution. The I/O devices 40and 50 are located on a chassis 11 of the fire truck 10, which includesboth the body and the underbody of the fire truck 10.

In the illustrated embodiment, two different types of interface modulesare used. The interface modules 20 interface mainly with switches andlow power indicators, such as LEDs that are integrally fabricated with aparticular switch and that are used to provide visual feedback to anoperator regarding the state of the particular switch. For this reason,the interface modules 20 are sometimes referred to herein as “SIMs”(“switch interface modules”). Herein, the reference numeral “20” is usedto refer to the interface modules 20 collectively, whereas the referencenumerals 21, 22 and 23 are used to refer to specific ones of theinterface modules 20.

The interface modules 30 interface with the remaining I/O devices 40 and50 on the vehicle that do not interface to the interface modules 20, andtherefore are sometimes referred to herein as “VIMs” (“vehicle interfacemodules”). The interface modules 30 are distinguishable from theinterface modules 20 mainly in that the interface modules 30 are capableof handling both analog and digital inputs and outputs, and in that theyare capable of providing more output power to drive devices such asgauges, valves, solenoids, vehicle lighting and so on. The analogoutputs may be true analog outputs or they may be pulse width modulationoutputs that are used to emulate analog outputs. Herein, the referencenumeral “30” is used to refer to the interface modules 30 collectively,whereas the reference numerals 31, 32, 33, 34 and 35 are used to referto specific ones of the interface modules 30.

Although two different types of interface modules are used in theillustrated embodiment, depending on the application, it may bedesirable to use only a single type of interface module in order toreduce inventory requirements. Additionally, while in FIG. 1 three ofthe interface modules 20 and five of the interface modules 30 are shown,this arrangement is again simply one example. It may be desirable toprovide each interface module with more I/O points in order to reducethe number of interface modules that are required, or to use moreinterface modules with a smaller number of I/O points in order to makethe control system 12 more highly distributed. Of course, the number ofinterface modules will also be affected by the total number of I/Opoints in the control system.

FIG. 1 shows an approximate distribution of the interface modules 20 and30 throughout the fire truck 10. In general, in order to minimizewiring, the interface modules 20 and 30 are placed so as to be locatedas closely as possible to the input devices 40 from which input statusinformation is received and the output devices 50 that are controlled.As shown in FIG. 1, there is a large concentration of interface modules20 and 30 near the front of the fire truck 10, with an additionalinterface module 34 at mid-length of the fire truck 10 and anotherinterface module 35 at the rear of the fire truck 10. The largeconcentration of interface modules 20 and 30 at the front of the firetruck 10 is caused by the large number of switches (including those withintegral LED feedback output devices) located in a cab of the fire truck10, as well as the large number of other output devices (gauges,lighting) which tend to be located in the cab or otherwise near thefront of the fire truck 10. The interface module 34 that is located inthe middle of the truck is used in connection with I/O devices 40 and 50that are located at the fire truck pump panel (i.e., the operator panelthat has I/O devices for operator control of the fire truck's pumpsystem). The interface module 35 that is located at the rear of the firetruck 10 is used in connection with lighting and other equipment at therear of the fire truck 10.

The advantage of distributing the interface modules 20 and 30 in thismanner can be more fully appreciated with reference to FIG. 2, whichshows the interconnection of the interface modules 20 and 30. As shownin FIG. 2, the interface modules 20 and 30 receive power from a powersource 100 by way of a power transmission link 103. The powertransmission link 103 may comprise for example a single power line thatis routed throughout the fire truck 10 to each of the interface modules20 and 30. The interface modules then distribute the power to the outputdevices 50, which are more specifically designated with the referencenumbers 51 a, 52 a, 53 a, 54 a-c, 55 a-c, 56 a-b, 57 a-c and 58 a-d inFIG. 2.

It is therefore seen from FIGS. 1 and 2 that the relative distributionof the interface modules 20 and 30 throughout the fire truck 10 incombination with the arrangement of the power transmission link 103allows the amount of wiring on the fire truck 10 to be dramaticallyreduced. The power source 100 delivers power to the interface modules 20and 30, which act among other things as power distribution centers, andnot directly to the output devices 50. Because the interface modules 20and 30 are located so closely to the I/O devices 40 and 50, most of theI/O devices can be connected to the interface modules 20 and 30 usingonly a few feet of wire or less. This eliminates the need for a wireharness that extends the length of the fire truck (about forty feet) toestablish connections for each I/O devices 40 and 50 individually.

Continuing to refer to FIG. 2, the switch interface modules 20 and theinterconnection of the interface modules 20 with various I/O deviceswill now be described in greater detail. The interface modules 20 aremicroprocessor-based, as previously noted, and include a microprocessorthat executes a program to enable communication over the communicationnetwork 60, as detailed below.

The same or a different microprocessor of the interface modules 20 mayalso be used to process input signals received from the input devices40. In particular, the interface modules 20 preferably perform debouncefiltering of the switch inputs, so as to require that the position ofthe switch become mechanically stable before a switch transition isreported to the central control unit 14. For example, a delay of fiftymilliseconds may be required before a switch transition is reported.Performing this filtering at the interface modules 20 reduces the amountof processing that is required by the central control unit 14 tointerpret switch inputs, and also reduces the amount of communicationthat is required over the communication network 60 because each switchtransition need not be reported.

Physically, the interface modules 20 may be placed near the headliner ofa cab 17 of the fire truck 10. Traditionally, it is common practice tolocate panels of switches along the headliner of the cab for easy accessby an operator of the fire truck. Additionally, as detailed below, inthe preferred embodiment, the interface modules 20 are connected toswitches that have integrally fabricated LEDs for indicating the stateof the output device controlled by the switch to provide maximumoperator feedback. These LEDs are output devices which are connected tothe interface modules 20. Therefore, by locating the interface modulesnear the headliner of the cab, the amount of wiring required to connectthe interface modules 20 not only to the switches and but also to theLED indicators is reduced.

In the preferred embodiment, the interface modules 20 have between tenand twenty-five each of inputs and outputs and, more preferably, havesixteen digital (on/off switch) inputs and sixteen LED outputs. Most ofthese inputs and outputs are utilized in connection with switches havingintegrally fabricated LEDs. However, it should be noted that there neednot be a one-to-one correspondence between the switches and the LEDs,and that the inputs and the outputs of the interface modules 20 need notbe in matched pairs. For example, some inputs may be digital sensors(without a corresponding output device) and some of the outputs may beordinary digital indicators (without a corresponding input device).Additionally, the LED indicators associated with the switch inputs forthe interface module 21 could just as easily be driven by the interfacemodule 23 as by the interface module 21, although this arrangement isnot preferred. Of course, it is not necessary that all of the inputs andoutputs on a given interface module 20 be utilized and, in fact, it islikely that some will remain unutilized.

One way of establishing a dedicated link between the I/O devices 40 and50 and the interface modules 20 is through the use of a simple hardwiredlink. Considering for example an input device which is a switch, oneterminal of the switch may be connected (e.g., by way of a harnessconnector) to an input terminal of the interface module 20 and the otherterminal of the switch may be tied high (bus voltage) or low (ground).Likewise, for an output device which is an LED, one terminal of the LEDmay be connected to an output terminal of the interface module 20 andthe other terminal of the LED may again be tied high or low. Otherdedicated links, such as RF links, could also be used.

To provide maximum operator feedback, the LEDs that are located with theswitches have three states, namely, off, on, and blinking. The off stateindicates that the switch is off and therefore that the devicecontrolled by the switch is off. Conversely, the on state indicates thatthe switch is on and that the device controlled by the switch is on. Theblinking state indicates that the control system 12 recognizes that aswitch is on, but that the device which the switch controls isnevertheless off for some other reason (e.g., due to the failure of aninterlock condition, or due to the operation of the load manager or loadsequencer). Notably, the blinking LED feedback is made possible by thefact that the LEDs are controlled by the control unit 14 and notdirectly by the switches themselves, since the switches themselves donot necessarily know the output state of the devices they control.

A specific example will now be given of a preferred interconnection ofthe interface modules 21, 22, and 23 with a plurality of I/O devices 40and 50. Many or all of the I/O devices 40 and 50 could be the same asthose that have previously been used on fire trucks. Additionally, itshould be noted that the example given below is just one example, andthat a virtually unlimited number of configurations are possible. Thisis especially true since fire trucks tend to be sold one or two at atime and therefore each fire truck that is sold tends to be unique atleast in some respects.

In FIG. 2, the interface module 21 receives inputs from switches 41 athat control the emergency lighting system of the fire truck. Aspreviously noted, the emergency lighting system includes the flashingemergency lights (usually red and white) that are commonly associatedwith fire trucks and that are used to alert other motorists to thepresence of the fire truck on the roadway or at the scene of a fire. Oneof the switches 41 a may be an emergency master on/off (E-master) switchused to initiate load sequencing, as described in greater detail below.The interface module 21 may also be connected, for example, to switches41 b that control the emergency siren and horn. The interface module 21is also connected to LEDs 51 a that are integrally located in theswitches 41 a and 41 b and that provide operator feedback regarding thepositions of the switches 41 a and 41 b, as previously described.

The interface module 22 receives inputs from switches 42 a that controllighting around the perimeter of the fire truck 10, switches 42 b thatcontrol scene lighting, and switches 42 c that control lighting whichaids the operators in viewing gauges and other settings at the pumppanel. The interface module 22 is also connected to LEDs 52 a that areintegrally located in the switches 42 a, 42 b and 42 c and that provideoperator feedback regarding the positions of the switches 42 a, 42 b and42 c.

The interface module 23 receives inputs from switches 43 a that controlheating and air conditioning, and switches 43 b that controlsmiscellaneous other electrical devices. The interface module 23 isconnected to LED indicators, some of which may be integrally locatedwith the switches 43 a and 43 b and others of which may simply be an LEDindicator that is mounted on the dashboard or elsewhere in the cab ofthe fire truck 10.

Continuing to refer to FIG. 2, the vehicle interface modules 30 and theinterconnection of the interface modules 20 with various I/O deviceswill now be described in greater detail. As previously mentioned, theinterface modules 30 are distinguishable from the interface modules 20mainly in that the interface modules 30 are capable of handling bothanalog and digital inputs and outputs, and in that they are capable ofproviding more output power to drive output devices such asdigitally-driven gauges, solenoids, and so on. The interface modules 30preferably have between fifteen and twenty-five each inputs and outputsand, more preferably, have twenty inputs (including six digital inputs,two frequency counter inputs, and six analog inputs) and twenty outputs(including six outputs that are configurable as analog outputs).

Like the interface modules 20, the interface modules 30 aremicroprocessor-based and include a microprocessor that executes aprogram to enable communication over the communication network 60. Thesame or a different microprocessor of the interface modules 30 may alsobe used to process input signals received from the input devices 40 andto process output signals transmitted to the output devices 50.

For the interface modules 30, this processing includes not only debouncefiltering, in the case of switch inputs, but also a variety of othertypes of processing. For example, for analog inputs, this processingincludes any processing that is required to interpret the inputs fromanalog-to-digital (A/D) converters, including converting units. Forfrequency inputs, this processing includes any processing that isrequired to interpret inputs from frequency-to-digital converters,including converting units. This processing also includes other simplefiltering operations. For example, in connection with one analog input,this processing may include notifying the central control unit 14 of thestatus of an input device only every second or so. In connection withanother analog input, this processing may include advising the centralcontrol unit 14 only when the status of the input device changes by apredetermined amount. For analog output devices, this processingincludes any processing that is required to interpret the outputs fordigital-to-analog (D/A) converters, including converting units. Fordigital output devices that blink or flash, this processing includesimplementing the blinking or flashing (i.e., turning the output deviceon and off at a predetermined frequency) based on an instruction fromthe central control unit 14 that the output device should blink orflash. In general, the processing by the interface modules 30 reducesthe amount of information which must be communicated over thecommunication link, and also reduces the amount of time that the centralcontrol unit 14 must spend processing minor changes in analog inputstatus.

Preferably, the configuration information required to implement the I/Oprocessing that has just been described is downloaded from the centralcontrol unit 14 to each interface module 30 (and each interface module20) at power-up. Additionally, the harness connector that connects toeach of the interface modules 20 and 30 are preferably electronicallykeyed, such that being connected to a particular harness connectorprovides the interface modules 20 and 30 with a unique identificationcode (for example, by tying various connector pins high and low toimplement a binary code). The advantage of this approach is that theinterface modules 20 and 30 become interchangeable devices that arecustomized only at power-up. As a result, if one of the interfacemodules 30 malfunctions, for example, a new interface module 30 can beplugged into the control system 12, customized automatically at power-up(without user involvement), and the control system 12 then becomes fullyoperational. This enhances the maintainability of the control system 12.

A specific example will now be given of a preferred interconnection ofthe interface modules 31, 32, and 33 with a plurality of I/O devices 40and 50. This example continues the example that was started inconnection with the interface modules 21, 22, and 23. Again, it shouldbe noted that the configuration described herein is just one example.

The interface modules 31, 32, 33, 34 and 35 all receive inputs fromadditional switches and sensors 44 a, 45 a, 46 a, 47 a and 48 a. Theswitches may be additional switches that are located in the cab of thefire truck or elsewhere throughout the vehicle, depending on thelocation of the interface module. The sensors may be selected ones of avariety of sensors that are located throughout the fire truck. Thesensors may be used to sense the mechanical status of devices on thefire truck, for example, whether particular devices are engaged ordisengaged, whether particular devices are deployed, whether particulardoors on the fire truck are open or closed, and so on. The sensors mayalso be used to sense fluid levels such as fuel level, transmissionfluid level, coolant level, foam pressure, oil level, and so on.

In addition to the switches and sensors 44 a, the interface module 31 isalso connected to a portion 54 a of the emergency lighting system. Theemergency lighting system includes emergency lights (usually red andwhite) at the front, side and rear of the fire truck 10. The emergencylights may, for example, be in accordance with the guidelines providedby the National Fire Protection Association. Because the interfacemodule 31 is located at the front of the fire truck, the interfacemodule 31 is connected to the red and white emergency lights at thefront of the fire truck.

The interface module 31 is also connected to gauges and indicators 54 bwhich are located on the dashboard of the fire truck 10. The gauges mayindicate fluid levels such as fuel level, transmission fluid level,coolant level, foam pressure, oil level and so on. The indicators mayinclude, for example, indicators that are used to display danger,warning and caution messages, warning lights, and indicators thatindicate the status of various mechanical and electrical systems on thefire truck. The interface module 31 may also be connected, for example,to an emergency sound system including an emergency siren and emergencyair horns 54 c, which are used in combination with the emergency lights54 a.

In addition to the switches and sensors 45 a, the interface module 32 isalso connected to perimeter lighting 55 a, scene lighting 55 b andutility lighting 55 c. The perimeter lighting 55 a illuminates theperimeter of the fire truck 10. The scene lighting 55 b includes brightflood lights and/or spot lights to illuminate the work area at a fire.The utility lighting 55 c includes lighting used to light operatorpanels, compartments and so on of the fire truck 10.

In addition to the switches and sensors 46 a, the interface module 33 isalso connected to PTO sensors 46 b. The PTO sensors 46 b monitor thestatus of a power take-off mechanism 97 (see FIG. 1), which divertsmechanical power from the engine/transmission from the wheels to othermechanical subsystems, such as the pump system, an aerial system and soon. The interface module 33 is also connected to a portion 56 a of theFMVSS (Federal Motor Vehicle Safety Standard) lighting. The FMVSSlighting system includes the usual types of lighting systems that arecommonly found on most types of vehicles, for example, head lights, taillights, brake lights, directional lights (including left and rightdirectionals), hazard lights, and so on. The interface module 33 is alsoconnected to the heating and air conditioning 56 b.

In addition to the switches and sensors 47 a, the interface module 34,which is disposed near the pump panel, is connected to pump panelswitches and sensors 47 a, pump panel gauges and indicators 57 a, pumppanel lighting 57 b, and perimeter lighting 57 c. The pump system may bemanually controlled or may be automatically controlled through the useof electronically controlled valves. In either case, the various fluidpressures are measured by sensors and displayed on the gauges andindicators 57 a.

Finally, in addition to the switches and sensors 48 a, the interfacemodule 35 is also connected to emergency lighting 58 a, scene lighting58 b, FMVSS lighting 58 c, and the utility lighting 58 d. These lightingsystems have been described above.

The interface modules 20 and the interface modules 30 are connected tothe central control unit 14 by the communication network 60. Thecommunication network may be implemented using a network protocol, forexample, which is in compliance with the Society of Automotive Engineers(SAE) J1708/1587 and/or J1939 standards. The particular network protocolthat is utilized is not critical, although all of the devices on thenetwork should be able to communicate effectively and reliably.

The transmission medium may be implemented using copper or fiber opticcable. Fiber optic cable is particularly advantageous in connection withfire trucks because fiber optic cable is substantially immune toelectromagnetic interference, for example, from communication antennaeon mobile news vehicles, which are common at the scenes of fires.Additionally, fiber optic cable is advantageous because it reduces RFemissions and the possibility of short circuits as compared tocopper-based networks. Finally, fiber optic cable is advantageousbecause it reduces the possibility of electrocution as compared tocopper in the event that the cable accidentally comes into contact withpower lines at the scene of a fire.

Also connected to the communication network 60 are a plurality ofdisplays 81 and 82. The displays 81 and 82 permit any of the datacollected by the central control unit 14 to be displayed to thefirefighters in real time. In practice, the data displayed by thedisplays 81 and 82 may be displayed in the form of text messages and maybe organized into screens of data (given that there is too much data todisplay at one time) and the displays 81 and 82 may include membranepushbuttons that allow the firefighters to scroll through, page through,or otherwise view the screens of data that are available. Additionally,although the displays 81 and 82 are both capable of displaying any ofthe information collected by the central control unit 14, in practice,the displays 81 and 82 are likely to be used only to display selectedcategories of information. For example, assuming the display 81 islocated in the cab and the display 82 is located at the pump panel, thedisplay 81 is likely to be used to display information that pertains todevices which are controlled from within the cab, whereas the display 82is likely to be used to display information pertaining to the operationof the pump panel. Advantageously, the displays 81 and 82 givefirefighters instant access to fire truck information at a singlelocation, which facilitates both normal operations of the fire truck aswell as troubleshooting if problems arise.

Also shown in FIG. 2 is a personal computer 85 which is connected to thecontrol unit 14 by way of a communication link 86, which may be a modemlink, an RS-232 link, an Internet link, and so on. The personal computer85 allows diagnostic software to be utilized for remote or localtroubleshooting of the control system 12, for example, through directexamination of inputs, direct control of outputs, and viewing andcontrolling internal states, including interlock states. Because all I/Ostatus information is stored in the central control unit 14, thisinformation can be easily accessed and manipulated by the personalcomputer 85. If a problem is encountered, the personal computer can beused to determine whether the central control unit 14 considers all ofthe interface modules 20 and 30 to be “on-line” and, if not, theoperator can check for bad connections and so on. If a particular outputdevice is not working properly, the personal computer 85 can be used totrace the I/O status information from the switch or other input devicethrough to the malfunctioning output device. For example, the personalcomputer 85 can be used to determine whether the switch state is beingread properly, whether all interlock conditions are met, and so on.

The personal computer 85 also allows new firmware to be downloaded tothe control unit 14 remotely (e.g., from a different city or state orother remote location by way of the Internet or a telephone link) by wayof the communication link 86. The firmware can be firmware for thecontrol unit 14, or it can be firmware for the interface modules 20 and30 that is downloaded to the control unit 14 and then transmitted to theinterface modules 20 and 30 by way of the communication network 60.

Finally, referring back to FIG. 1, several additional systems are shownwhich will now be briefly described before proceeding to a discussion ofthe operation of the control system 12. In particular, FIG. 1 shows anengine system including an engine 92 and an engine control system 91, atransmission system including a transmission 93 and a transmissioncontrol system 94, and an anti-lock brake system including an anti-lockbrake control system 95 and anti-lock brakes 96. The transmission 93 ismechanically coupled to the engine 92, and is itself furthermechanically coupled to a PTO system 97. The PTO system 97 allowsmechanical power from the engine to be diverted to water pumps, aerialdrive mechanisms, stabilizer drive mechanisms, and so on. Incombination, the engine system, the transmission system and the PTOsystem form the power train of the fire truck 10.

The control systems 92, 94 and 95 may be connected to the centralcontrol unit 14 using the same or a different communication network thanis used by the interface modules 30 and 40. In practice, the controlsystems 92, 94 and 95 are likely to be purchased as off-the-shelfsystems, since most fire truck manufacturers purchase rather thanmanufacture engine systems, transmission systems and anti-lock brakesystems. As a result, it is likely that the control systems 92, 94 and95 will use a variety of different communication protocols and thereforethat at least one additional communication network will be required.

By connecting the systems 92, 94 and 95 to the central control unit 14,an array of additional input status information becomes available to thecontrol system 12. For example, for the engine, this allows the centralcontrol unit 14 to obtain I/O status information pertaining to enginespeed, engine hours, oil temperature, oil pressure, oil level, coolantlevel, fuel level, and so on. For the transmission, this allows thecentral control unit 14 to obtain, for example, information pertainingtransmission temperature, transmission fluid level and/or transmissionstate (1st gear, 2nd gear, and so on). Assuming that an off-the-shelfengine or transmission system is used, the information that is availabledepends on the manufacturer of the system and the information that theyhave chosen to make available.

Connecting the systems 92, 94 and 95 to the central control unit 14 isadvantageous because it allows information from these subsystems to bedisplayed to firefighters using the displays 81 and 82. This also allowsthe central control unit 14 to implement various interlock conditions asa function of the state of the transmission, engine or brake systems.For example, in order to turn on the pump system (which is mechanicallydriven by the engine and the transmission), an interlock condition maybe implemented that requires that the transmission be in neutral or 4thlockup (i.e., fourth gear with the torque converter locked up), so thatthe pump can only be engaged when the wheels are disengaged from thepower train. The status information from these systems can therefore betreated in the same manner as I/O status information from any otherdiscrete I/O device on the fire truck 10. It may also be desirable toprovide the central control unit 14 with a limited degree of controlover the engine and transmission systems, for example, enabling thecentral control unit 14 to issue throttle command requests to the enginecontrol system 91. This allows the central control unit to control thespeed of the engine and therefore the voltage developed across thealternator that forms part of the power source 100.

From the foregoing description, a number advantages of the preferredfire truck control system are apparent. In general, the control systemis easier to use, more flexible, more robust, and more reliable thanexisting control systems. In addition, because of these advantages, thecontrol system also increases firefighter safety because the many of thefunctions that were previously performed by firefighters are performedautomatically, and the control system also makes possible features thatwould otherwise be impossible or at least impractical. Therefore,firefighters are freed to focus on fighting fires.

The control system is easier to use because the control system providesa high level of cooperation between various vehicle subsystems. Thecontrol system can keep track of the mode of operation of the firetruck, and can control output devices based on the mode of operation.The functions that are performed on the fire truck are more fullyintegrated to provide a seamless control system, resulting in betterperformance.

The control system is robust and can accept almost any new featurewithout changes in wiring. Switches are connected to interface modulesand not to outputs directly, and new features can be programmed into thecontrol program executed by the central control unit. A system can bemodified by adding a new switch to an existing interface module, or bymodifying the function of an existing switch in the control program.Therefore, modifying a system that is already in use is easy becauselittle or no wiring changes are required.

Additionally, because the control system has access to input statusinformation from most or all of the input devices on the fire truck andhas control over most or all of the output devices on the fire truck, ahigh level of cooperation between the various subsystems on the firetruck is possible. Features that require the cooperation of multiplesubsystems are much easier to implement.

The fire truck is also easier to operate because there is improvedoperator feedback. Displays are provided which can be used to determinethe I/O status of any piece of equipment on the vehicle, regardless ofthe location of the display. Additionally, the displays facilitatetroubleshooting, because troubleshooting can be performed in real timeat the scene of a fire when a problem is occurring. Troubleshooting isalso facilitated by the fact that the displays are useable to displayall of the I/O status information on the fire truck. There is no needfor a firefighter to go to different locations on the fire truck toobtain required information. Troubleshooting is also facilitated by theprovision of a central control unit which can be connected by modem toanother computer. This allows the manufacturer to troubleshoot the firetruck as soon as problems arise.

LED indicators associated with switches also improve operator feedback.The LEDs indicate whether the switch is considered to be off or on, orwhether the switch is considered to be on but the output devicecontrolled by the switch is nevertheless off due to some other conditionon the fire truck.

Because the control system is easier to use, firefighter safety isenhanced. When a firefighter is fighting fires, the firefighter is ableto more fully concentrate on fighting the fire and less on having toworry about the fire truck. To the extent that the control systemaccomplishes tasks that otherwise would have to be performed by thefirefighter, this frees the firefighter to fight fires.

The control system is also more reliable and maintainable, in partbecause relay logic is replaced with logic implemented in a controlprogram. The logic in the control program is much easier totroubleshoot, and troubleshooting can even occur remotely by modem. Alsomechanical circuit breakers can be replaced with electronic control,thereby further reducing the number of mechanical failure points andmaking current control occur more seamlessly. The simplicity of thecontrol system minimizes the number of potential failure points andtherefore enhances reliability and maintainability.

The system is also more reliable and more maintainable because there isless wire. Wiring is utilized only to established dedicated linksbetween input/output devices and the interface module to which they areconnected. The control system uses distributed power distribution anddata collecting. The interface modules are interconnected by a networkcommunication link instead of a hardwired link, thereby reducing theamount of wiring on the fire truck. Most wiring is localized wiringbetween the I/O devices and a particular interface module.

Additionally, the interface modules are interchangeable units. In thedisclosed embodiment, the interface modules 20 are interchangeable witheach other, and the interface modules 30 are interchangeable with eachother. If a greater degree of interchangeability is required, it is alsopossible to use only a single type of interface module. If the controlsystem were also applied to other types of equipment service vehicles(e.g., snow removal vehicles, refuse handling vehicles, cement/concretemixers, military vehicles such as those of the multipurpose modulartype, on/off road severe duty equipment service vehicles, and so on),the interface modules would even be made interchangeable acrossplatforms since each interface module views the outside world in termsof generic inputs and outputs, at least until configured by the centralcontrol unit. Because the interface modules are interchangeable,maintainability is enhanced. An interface module that begins tomalfunction due to component defects may be replaced more easily. Onpower up, the central control unit downloads configuration informationto the new interface module, and the interface module becomes fullyoperational. This enhances the maintainability of the control system.

Because the interface modules are microprocessor-based, the amount ofprocessing required by the central control unit as well as the amount ofcommunication that is necessary between the interface modules and thecentral control unit is reduced. The interface modules performpreprocessing of input signals and filter out less critical inputsignals and, as a result, the central control unit receives and respondsto critical messages more quickly.

B. Military Vehicle Control System

Referring now to FIG. 3, a preferred embodiment of a military vehicle1410 having a control system 1412 is illustrated. As previouslyindicated, the control system described above can be applied to othertypes of equipment service vehicles, such as military vehicles, becausethe interface modules view the outside world in terms of generic inputsand outputs. Most or all of the advantages described above in thecontext of fire fighting vehicles are also applicable to militaryvehicles. As previously described, however, it is sometimes desirable inthe context of military applications for the military vehicle controlsystem to be able to operate at a maximum level of effectiveness whenthe vehicle is damaged by enemy fire, nearby explosions, and so on. Inthis situation, the control system 1412 preferably incorporates a numberof additional features, discussed below, that increase the effectivenessof the control system 1412 in these military applications.

By way of overview, the control system 1412 comprises a plurality ofmicroprocessor-based interface modules 1420, a plurality of input andoutput devices 1440 and 1450 (see FIG. 4) that are connected to theinterface modules 1420, and a communication network 1460 thatinterconnects the interface modules 1420. The control system 1412preferably operates in the same manner as the control system 12 of FIGS.1-2, except to the extent that differences are outlined are below.

More specifically, in the illustrated embodiment, the control system1412 is used in connection with a military vehicle 1410 which is amultipurpose modular military vehicle. As is known, a multipurposemodule vehicle comprises a chassis and a variant module that is capableof being mounted on the chassis, removed, and replaced with anothervariant module, thereby allowing the same chassis to be used fordifferent types of vehicles with different types of functionalitydepending on which variant module is mounted to the chassis. In theillustrated embodiment, the military vehicle 1410 is a wrecker andincludes a wrecker variant module 1413 mounted on a chassis (underbody)1417 of the military vehicle 1410. The weight of the variant module 1413is supported by the chassis 1417. The variant module 1413 includes amechanical drive device 1414 capable of imparting motion to solid orliquid matter that is not part of the military vehicle 1410 to providethe military vehicle 1410 with a particular type of functionality. InFIG. 3, where the variant module 1413 is a wrecker variant, themechanical drive device is capable of imparting motion to a towedvehicle. As shown in FIG. 8, the variant module 1413 is removable andreplaceable with other types of variant modules, which may include adump truck variant 1418 a, a water pump variant 1418 b, a telephonevariant 1418 c, and so on. Thus, for example, the wrecker variant 1413may be removed and replaced with a water pump variant 1418 b having adifferent type of drive mechanism (a water pump) to provide a differenttype of functionality (pumper functionality). The I/O devices 1440 and1450 used by the vehicle 1410 include devices that are the same as orsimilar to the non-fire truck specific I/O devices of FIGS. 1-2 (i.e.,those types of I/O devices that are generic to most types of vehicles),as well as I/O devices that are typically found on the specific type ofvariant module chosen (in FIG. 3, a wrecker variant).

The interface modules 1420 are constructed in generally the same manneras the interface modules 20 and 30 and each include a plurality ofanalog and digital inputs and outputs. The number and type of inputs andoutputs may be the same, for example, as the vehicle interface modules30. Preferably, as described in greater detail below, only a single typeof interface module is utilized in order to increase the fieldserviceability of the control system 1412. Herein, the reference numeral1420 is used to refer to the interface modules 1420 collectively,whereas the reference numerals 1421-1430 are used to refer to specificones of the interface modules 1420. The interface modules are describedin greater detail in connection with FIGS. 4-6.

Also connected to the communication network 1460 are a plurality ofdisplays 1481 and 1482 and a data logger 1485. The displays 1481 and1482 permit any of the data collected by the control system 1412 to bedisplayed in real time, and also display warning messages. The displays1481 and 1482 also include membrane pushbuttons that allow the operatorsto scroll through, page through, or otherwise view the screens of datathat are available. The membrane pushbuttons may also allow operators tochange values of parameters in the control system 1412. The data logger1485 is used to store information regarding the operation of themilitary vehicle 1410. The data logger 1485 may also be used as a “blackbox recorder” to store information logged during a predetermined amountof time (e.g., thirty seconds) immediately prior to the occurrence ofone or more trigger events (e.g., events indicating that the militaryvehicle 1410 has been damaged or rendered inoperative, such as when anoperational parameter such as an accelerometer threshold has beenexceeded).

Finally, FIG. 3 shows an engine system including an engine 1492 and anengine control system 1491, a transmission system including atransmission 1493 and a transmission control system 1494, and ananti-lock brake system including an anti-lock brake control system 1495.These systems may be interconnected with the control system 1412 ingenerally the same manner as discussed above in connection with theengine 92, the engine control system 91, the transmission 93, thetransmission control system 94, and the anti-lock brake system 36 ofFIG. 1.

Referring now also to FIG. 4-6, the structure and interconnection of theinterface modules 1420 is described in greater detail. Referring firstto FIG. 4, the interconnection of the interface modules 1420 with apower source 1500 is described. The interface modules 1420 receive powerfrom the power source 1500 by way of a power transmission link 1502. Theinterface modules 1420 are distributed throughout the military vehicle1410, with some of the interface modules 1420 being located on thechassis 1417 and some of the interface modules 1420 being located on thevariant module 1413.

The control system is subdivided into three control systems including achassis control system 1511, a variant control system 1512, and anauxiliary control system 1513. The chassis control system 1511 includesthe interface modules 1421-1425 and the I/O devices 1441 and 1451, whichare all mounted on the chassis 1417. The variant control system 1512includes the interface modules 1426-1428 and the I/O devices 1442 and1452, which are all mounted on the variant module 1413. The auxiliarycontrol system 1513 includes the interface modules 1429-1430 and the I/Odevices 1443 and 1453, which may be mounted on either the chassis 1417or the variant module 1413 or both.

The auxiliary control system 1513 may, for example, be used to control asubsystem that is disposed on the variant module but that is likely tobe the same or similar for all variant modules (e.g., a lightingsubsystem that includes headlights, tail lights, brake lights, andblinkers). The inclusion of interface modules 1420 within a particularcontrol system may also be performed based on location rather thanfunctionality. For example, if the variant module 1413 has an aerialdevice, it may be desirable to have one control system for the chassis,one control system for the aerial device, and one control system for theremainder of the variant module. Additionally, although each interfacemodule 1420 is shown as being associated with only one of the controlsystems 1511-1513, it is possible to have interface modules that areassociated with more than one control system. It should also be notedthat the number of sub-control systems, as well as the number ofinterface modules, is likely to vary depending on the application. Forexample, a mobile command vehicle is likely to have more controlsubsystems than a wrecker variant, given the large number of I/O devicesusually found on mobile command vehicles.

The power transmission link 1502 may comprise a single power line thatis routed throughout the military vehicle 1410 to each of the interfacemodules 1420, but preferably comprises redundant power lines. Again, inorder to minimize wiring, the interface modules 1420 are placed so as tobe located as closely as possible to the input devices 1440 from whichinput status information is received and the output devices 1450 thatare controlled. This arrangement allows the previously-describedadvantages associated with distributed data collection and powerdistribution to be achieved. Dedicated communication links, which mayfor example be electric or photonic links, connect the interface modules1421-1430 modules with respective ones of the I/O devices, as previouslydescribed.

Referring next to FIG. 5, the interconnection of the interface modules1420 by way of the communication network 1460 is illustrated. Aspreviously indicated, the control system 1412 is subdivided into threecontrol systems 1511, 1512 and 1513. In accordance with thisarrangement, the communication network 1460 is likewise furthersubdivided into three communication networks 1661, 1662, and 1663. Thecommunication network 1661 is associated with the chassis control system1511 and interconnects the interface modules 1421-1425. Thecommunication network 1662 is associated with the variant control system1512 and interconnects the interface modules 1426-1428. Thecommunication network 1663 is associated with the auxiliary controlsystem 1513 and interconnects the interface modules 1429-1430.Communication between the control systems 1511-1513 occurs by way ofinterface modules that are connected to multiple ones of the networks1661-1663. Advantageously, this arrangement also allows the interfacemodules to reconfigure themselves to communicate over another network inthe event that part or all of their primary network is lost.

In practice, each of the communication networks 1661-1663 may be formedof two or more communication networks to provide redundancy within eachcontrol system. Indeed, the connection of the various interface modules1420 with different networks can be as complicated as necessary toobtain the desired level of redundancy. For simplicity, these potentialadditional levels of redundancy will be ignored in the discussion ofFIG. 5 contained herein.

The communication networks 1661-1663 may be implemented in accordancewith SAE J1708/1587 and/or J1939 standards, or some other networkprotocol, as previously described. The transmission medium is preferablyfiber optic cable in order to reduce the amount of electromagneticradiation that the military vehicle 1410 produces, therefore making thevehicle less detectable by the enemy. Fiber optic networks are also morerobust to the extent that a severed fiber optic cable is still usable tocreate two independent networks, at least with reduced functionality.

When the variant module 1413 is mounted on the chassis 1417, connectingthe chassis control system 1511 and the variant control system 1512 isachieved simply through the use of two mating connectors 1681 and 1682that include connections for one or more communication busses, power andground. The chassis connector 1682 is also physically and functionallymateable with connectors for other variant modules, i.e., the chassisconnector and the other variant connectors are not only capable ofmating physically, but the mating also produces a workable vehiclesystem. A given set of switches or other control devices 1651 on thedash (see FIG. 3) may then operate differently depending on whichvariant is connected to the chassis. Advantageously, therefore, it ispossible to provide a single interface between the chassis and thevariant module (although multiple interfaces may also be provided forredundancy). This avoids the need for a separate connector on thechassis for each different type of variant module, along with theadditional unutilized hardware and wiring, as has conventionally beenthe approach utilized.

Upon power up, the variant control system 1512 and the chassis controlsystem 1511 exchange information that is of interest to each other. Forexample, the variant control system 1512 may communicate the varianttype of the variant module 1413. Other parameters may also becommunicated. For example, information about the weight distribution onthe variant module 1413 may be passed along to the chassis controlsystem 1511, so that the transmission shift schedule of the transmission1493 can be adjusted in accordance with the weight of the variant module1413, and so that a central tire inflation system can control theinflation of tires as a function of the weight distribution of thevariant. Similarly, information about the chassis can be passed along tothe variant. For example, where a variant module is capable of beingused by multiple chassis with different engine sizes, engine informationcan be communicated to a wrecker variant module so that the wreckervariant knows how much weight the chassis is capable of pulling. Thus,an initial exchange of information in this manner allows the operationof the chassis control system 1511 to be optimized in accordance withparameters of the variant module 1413, and vice versa.

It may also be noted that the advantages obtained for military variantscan also be realized in connection with commercial variants. Thus, ablower module, a sweeper module, and a plow module could be provided forthe same chassis. This would allow the chassis to be used for a sweeperin summer and a snow blower or snow plow in winter.

As shown in FIG. 5, each control system 1511-1513 includes an interfacemodule that is designated “master” and another that is designated“deputy master.” The master interface module may for example be used asa nexus for communication with external devices. Thus, for example, thechassis control system 1511 includes a master interface module 1423 anda deputy master interface module 1422. Additional tiers of mastershipmay also be implemented in connection with the interface modules 1421,1424 and 1425.

The interface modules 1420 are assigned their respective ranks in thetiers of mastership based on their respective locations on the militaryvehicle 1410. A harness connector at each respective location of themilitary vehicle 1410 connects a respective one of the interface modules1420 to the remainder of the control system 1412. The harness connectoris electronically keyed, such that being connected to a particularharness connector provides an interface module 1420 with a uniqueidentification code or address M. For simplicity, the value M is assumedto be a value between 1 and N, where N is the total number of interfacemodules on the vehicle (M=10 in the illustrated embodiment).

The interface modules 1420 each store configuration information that,among other things, relates particular network addresses with particularranks of mastership. Thus, for example, when the interface module 1423boots up, it ascertains its own network address and, based on itsnetwork address, ascertains that it is the master of the control system1511. The interface module 1423 serves as the central control unit solong as the interface module 1423 is competent to do so. For example, ifit is determined that the interface module 1423 is no longer competentto serve as master (e.g., because the interface module 1423 has beendamaged in combat), then the interface module 1422 becomes the masterinterface module and begins serving as the central control unit. Thisdecision can be made, for example, by the interface module 1423 itself,based on a vote taken by the remaining interface modules 1420, or basedon a decision by the deputy master.

Referring next to FIG. 6, an exemplary one of the interface modules 1420is shown in greater detail. The interface modules 1420 each include amicroprocessor 1815 that is sufficiently powerful to allow eachinterface module to serve as the central control unit. The interfacemodules are identically programmed and each include a memory 1831 thatfurther includes a program memory 1832 and a data memory 1834. Theprogram memory 1832 includes BIOS (basic input/output system) firmware1836, an operating system 1838, and application programs 1840, 1842 and1844. The application programs include a chassis control program 1840,one or more variant control programs 1842, and an auxiliary controlprogram 1844. The data memory 1834 includes configuration information1846 and I/O status information 1848 for all of the modules 1420-1430associated with the chassis 1417 and its variant module 1413, as well asconfiguration information for the interface modules (N+1 to Z in FIG. 6)of other variant modules that are capable of being mounted to thechassis 1417.

It is therefore seen that all of the interface modules 1420 that areused on the chassis 1417 and its variant module 1413, as well as theinterface modules 1420 of other variant modules that are capable ofbeing mounted to the chassis 1417, are identically programmed andcontain the same information. Each interface module 1420 then utilizesits network address to decide when booting up which configurationinformation to utilize when configuring itself, and which portions ofthe application programs 1840-1844 to execute given its status as amaster or non-master member of one of the control systems 1511-1513. Theinterface modules are both physically and functionally interchangeablebecause the interface modules are capable of being plugged in at anyslot on the network, and are capable of performing any functions thatare required at that slot on the network.

This arrangement is highly advantageous. Because all of the interfacemodules 1420 are identically programmed and store the same information,the interface modules are physically and functionally interchangeablewithin a given class of vehicles. Thus, if an interface module 1420 onone variant module is rendered inoperative, but the variant module isotherwise operational, the inoperative interface module can be replacedwith an interface module scavenged from another inoperative vehicle.When the replacement interface module 1420 reboots, it will thenreconfigure itself for use in the new vehicle, and begin operating thecorrect portions of the application programs 1840-1844. This is the caseeven when the two vehicles are different types of vehicles.

Additionally, if a highly critical interface module is renderedinoperable, the highly critical interface module can be swapped with aninterface module that is less critical. Although the input/outputdevices associated with the less critical interface module will nolonger be operable, the input/output devices associated with the morecritical interface module will be operable. This allows theeffectiveness of the military vehicle to be maximized by allowingundamaged interface modules to be utilized in the most optimal manner.In this way, the field serviceability of the control system 1412 isdramatically improved. Further, the field serviceability of the controlsystem 1412 is also improved by the fact that only a single type ofinterface module is used, because the use of a single type of interfacemodule makes it easier to find replacement interface modules.

Additionally, as previously noted, each interface module 1420 stores I/Ostatus information for all of the modules 1420-1430 associated with thechassis 1417 and its variant module 1413. Therefore, each interfacemodule 1420 has total system awareness. As a result, it is possible tohave each interface module 1420 process its own inputs and outputs basedon the I/O status information in order to increase system responsivenessand in order to reduce the amount of communication that is required withthe central control unit. The main management responsibility of thecentral control unit or master interface module above and beyond theresponsibilities of all the other interface modules 1420 then becomes,for example, to provide a nexus for interface operations with devicesthat are external to the control system of which the central controlunit is a part.

Referring now to FIG. 7, FIG. 7 is a truth table that describes theoperation of the control system 1412 in the event of failure of one ofthe interface modules 1420 and/or one of the input devices 1440. Thearrangement shown in FIG. 7 allows the control system 1412 to be able tocontinue to operate in the event of failure using a “best guess” methodof controlling outputs.

In the example of FIG. 7, two output devices are controlled based on twoinput devices. For example, the first output device may be headlights ofthe military vehicle 1410, the first input device may be a combat switchor combat override switch that places the entire vehicle into a combatmode of operation, and the second input may be an operator switch foroperator control of the headlights. The second output device isdiscussed further below. For simplicity, only the input states of twobinary input devices are shown. In practice, of course, the controllogic for most output devices will usually be a function of more inputdevices, in some cases ten or more input devices including analog inputdevices. Nevertheless, the simplified truth table of FIG. 7 issufficient to obtain an understanding of this preferred aspect of theinvention.

The truth table of FIG. 7 shows a number of different possible inputstates and the corresponding output states. In the first two states,when the combat override switch (input #1) is off, then the headlights(output #1) are controlled as a function of the operator switch. Thus,if the operator switch is on, then the control system 1412 turns theheadlights on, and if the operator switch is off, then the controlsystem 1412 turns the headlights off. In the third and fourth inputstates, the combat override switch is on, and therefore the controlsystem 1412 turns the headlights off in order to make the vehicle lessdetectable by the enemy. It may be noted that the control system 1412ignores the input state of the second input device when the combatoverride switch is on. The third column in the truth table couldtherefore instead be the output of a safety interlock, since safetyinterlocks are another example of input information that is sometimesignored when a combat override is turned on. This would allow thecontrol system 1412 to take into account the urgency of a combatsituation while still also implementing safety functions to the extentthat they do not interfere with the operation of the vehicle 1410.

The truth table also has a number of additional states (five throughnine) corresponding to situations in which one or both of the inputs isdesignated as undetermined (“?” in FIG. 7). Thus, for example, in statesfive and six, the input state of the operator switch (input #2) isdesignated as undetermined. The undetermined state of the operatorswitch may be the result of the failure of the interface module thatreceives the input signal from the operator switch, a failure of theelectrical connection between the switch and the interface module,and/or a failure of the operator switch itself. In the fifth state, whenthe combat override switch is off and the state of the operator switchis undetermined, the control system 1412 turns on the headlights, basedon the assumption that if it is nighttime the operator wants the lightson and if it is daytime the operator does not have a strong preferenceeither way. In the sixth state, when the combat override switch is onand the state of the operator switch is undetermined, the control system1412 turns off the headlights, because the headlights should always beturned off in the combat mode of operation.

In states seven through nine, the input state of the combat overrideswitch (input #1) is designated as undetermined. The undetermined stateof the combat override switch may be caused by generally the samefactors that are liable to cause the state of the operator switch to beundetermined. In all of these states, the control system 1412 turns offthe headlights, based on the worst case assumption that the militaryvehicle may be in combat and that therefore the headlights should beturned off.

The arrangement shown in FIG. 7 is thus applied to all output devices1450 on the military vehicle. In this way, the control logic forcontrolling the output devices is expanded to take into account a third“undetermined” state for each of the input devices, and an entireadditional layer of failure management is added to the control logic. Inthis way, the control system 1412 is able to remain operational (atleast in a best guess mode) when the input states of one or more inputdevices cannot be determined. This prevents output devices that have anoutput state based on the input state of a given input device from beingcrippled when a system failure causes one or more input devices to belost.

This arrangement also allows the output state of each output device tobe programmed individually in failure situations. In other words, when agiven input device is lost, the control system can be programmed toassume for purposes of some output devices (using the above describedtruth table arrangement) that the input device is on and to assume forthe purposes of other output devices that the input device is off. Forexample, in FIG. 7, if output device #2 is another output device that iscontrolled by the same operator switch, the control system can beprogrammed to assume for purposes of output device #2 that the operatorswitch is off in state five rather than on, such that the control systemturns off the output device #2 in state five. In this way, it is notnecessary to assume the same input state for purposes of all outputdevices.

It may also be noted that military vehicles tend to make widespread useof redundant sensors. In this case, by connecting the redundant sensorsto different ones of the interface modules, the state table for eachoutput device can be modified to accept either input, thereby making itpossible for the control system 1412 to obtain the same information by adifferent route. Further, if the redundant sensors disagree on the inputstatus of a system parameter, then this disagreement itself can betreated as an undetermined input state of an input device. In this way,rather than using a voting procedure in which the sensors vote on thestate of the input device for purposes of all output devices, theuncertainty can be taken into account and best guess decisions regardinghow to operate can be made for each of the various output devicesindividually.

As previously described, each interface module 1420 has total systemawareness. Specifically, the data memory 1834 of each interface module1420 stores I/O status information 1848 for not only local I/O devices1440 and 1450 but also for non-local I/O devices 1440 and 1450 connectedto remaining ones of the interface modules 1420. Referring now to FIGS.9-12, a preferred technique for transmitting I/O status informationbetween the interface modules 1420 will now be described. Although thistechnique is primarily described in connection with the chassis controlsystem 1511, this technique is preferably also applied to the variantcontrol system 1512 and the auxiliary control system 1513, and/or in thecontrol system 12.

Referring first to FIG. 9, as previously described, the chassis controlsystem 1511 includes the interface modules 1421-1425, the input devices1441, and the output devices 1451. Also shown in FIG. 9 are the display1481, the data logger 1485, and the communication network 1661 whichconnects the interface modules 1421-1425. In practice, the system mayinclude additional devices, such as a plurality of switch interfacemodules connected to additional I/O devices, which for simplicity arenot shown. The switch interface modules may be the same as the switchinterface modules 20 previously described and, for example, may beprovided in the form of a separate enclosed unit or in the more simpleform of a circuit board mounted with associated switches and low poweroutput devices. In practice, the system may include other systems, suchas a display interface used to drive one or more analog displays (suchas gauges) using data received from the communication network 1661. Anyadditional modules that interface with I/O devices preferably broadcastand receive I/O status information and exert local control in the samemanner as detailed below in connection with the interface modules1421-1425. As previously noted, one or more additional communicationnetworks may also be included which are preferably implemented inaccordance with SAE J1708/1587 and/or J1939 standards. The communicationnetworks may be used, for example, to receive I/O status informationfrom other vehicle systems, such as an engine or transmission controlsystem. Arbitration of I/O status broadcasts between the communicationnetworks can be performed by one of the interface modules 1420.

To facilitate description, the input devices 1441 and the output devices1451 have been further subdivided and more specifically labeled in FIG.9. Thus, the subset of the input devices 1441 which are connected to theinterface module 1421 are collectively labeled with the referencenumeral 1541 and are individually labeled as having respective inputstates I-11 to I-15. Similarly, the subset of the output devices 1451which are connected to the interface module 1421 are collectivelylabeled with the reference numeral 1551 and are individually labeled ashaving respective output states O-11 to O-15. A similar pattern has beenfollowed for the interface modules 1422-1425, as summarized in Table Ibelow:

TABLE I Interface Input Output Module Devices Input States DevicesOutput States 1421 1541 I-11 to I-15 1551 O-11 to O-15 1422 1542 I-21 toI-25 1552 O-21 to O-25 1423 1543 I-31 to I-35 1553 O-31 to O-35 14241544 I-41 to I-45 1554 O-41 to O-45 1425 1545 I-51 to I-55 1555 O-51 toO-55

Of course, although five input devices 1441 and five output devices 1451are connected to each of the interface modules 1420 in the illustratedembodiment, this number of I/O devices is merely exemplary and adifferent number of devices could also be used, as previously described.

The interface modules 1420 each comprise a respective I/O status table1520 that stores information pertaining to the I/O states of the inputand output devices 1441 and 1451. Referring now to FIG. 10, an exemplaryone of the I/O status tables 1520 is shown. As shown in FIG. 10, the I/Ostatus table 1520 stores I/O status information pertaining to each ofthe input states I-11 to I-15, I-21 to I-25, I-31 to I-35, I-41 to I-45,and I-51 to I-55 of the input devices 1541-1545, respectively, and alsostores I/O status information pertaining to each of the output statesO-11 to O-15, O-21 to O-25, O-31 to O-35, O-41 to O-45, and O-51 to O-55of the output devices 1551-1555, respectively. The I/O status tables1520 are assumed to be identical, however, each I/O status table 1520 isindividually maintained and updated by the corresponding interfacemodule 1420. Therefore, temporary differences may exist between the I/Ostatus tables 1520 as updated I/O status information is received andstored. Although not shown, the I/O status table 1520 also stores I/Ostatus information for the interface modules 1426-1428 of the variantcontrol system 1512 and the interface modules 1429-1430 of the auxiliarycontrol system 1513.

In practice, although FIG. 10 shows the I/O status information beingstored next to each other, the memory locations that store the I/Ostatus information need not be contiguous and need not be located in thesame physical media. It may also be noted that the I/O status table 1520is, in practice, implemented such that different I/O status are storedusing different amounts of memory. For example, some locations store asingle bit of information (as in the case of a digital input device ordigital output device) and other locations store multiple bits ofinformation (as in the case of an analog input device or an analogoutput device). The manner in which the I/O status table is implementedis dependent on the programming language used and on the different datastructures available within the programming language that is used. Ingeneral, the term I/O status table is broadly used herein to encompassany group of memory locations that are useable for storing I/O statusinformation.

Also shown in FIG. 10 are a plurality of locations that storeintermediate status information, labeled IM-11, IM-21, IM-22, and IM-41.The intermediate states IM-11, IM-21, IM-22, and IM-41 are processedversions of selected I/O states. For example, input signals may beprocessed for purposes of scaling, unit conversion and/or calibration,and it may be useful in some cases to store the processed I/O statusinformation. Alternatively, the intermediate states IM-11, IM-21, IM-22,and IM-41 may be a function of a plurality of I/O states that incombination have some particular significance. The processed I/O statusinformation is then transmitted to the remaining interface modules 1420.

Referring now to FIGS. 11-12, FIG. 11 is a flowchart describing theoperation of the control system of FIG. 9, and FIG. 12 is a data flowdiagram describing data flow through an exemplary interface moduleduring the process of FIG. 11. As an initial matter, it should be notedthat although FIG. 11 depicts a series of steps which are performedsequentially, the steps shown in FIG. 11 need not be performed in anyparticular order. In practice, for example, modular programmingtechniques are used and therefore some of the steps are performedessentially simultaneously. Additionally, it may be noted that the stepsshown in FIG. 11 are performed repetitively during the operation of theinterface module 1421, and some of the steps are in practice performedmore frequently than others. For example, input information is acquiredfrom the input devices more often than the input information isbroadcast over the communication network. Although the process of FIG.11 and the data flow diagram of FIG. 12 are primarily described inconnection with the interface module 1421, the remaining interfacemodules 1422-1425 operate in the same manner.

At step 1852, the interface module 1421 acquires input statusinformation from the local input devices 1541. The input statusinformation, which pertains to the input states I-11 to I-15 of theinput devices 1541, is transmitted from the input devices 1541 to theinterface module 1421 by way of respective dedicated communicationlinks, as previously described. At step 1854, the input statusinformation acquired from the local input devices 1541 is stored in theI/O status table 1520 at a location 1531. For the interface module 1421,the I/O devices 1541 and 1551 are referred to as local I/O devices sincethe I/O devices 1541 and 1551 are directly coupled to the interfacemodule 1421 by way of respective dedicated communication links, asopposed to the remaining non-local I/O devices and 1542-1545 and1552-1555 which are indirectly coupled to the interface module 1421 byway of the communication network 1661.

At step 1856, the interface module 1421 acquires I/O status informationfor the non-local input devices 1542-1545 and the non-local outputdevices 1552-1555 by way of the communication network 1661.Specifically, the interface module 1421 acquires input statusinformation pertaining to the input states I-21 to I-25, I-31 to I-35,I-41 to I-45, I-51 to I-55 of the input devices 1542-1545, respectively,and acquires output status information pertaining to the output statesO-21 to O-25, O-31 to O-35, O-41 to O-45, O-51 to O-55 of the outputdevices 1552-1555. The input status information and the output statusinformation are stored in locations 1533 and 1534 of the I/O statustable 1520, respectively.

At step 1860, the interface module 1421 determines desired output statesO-11 to O-15 for the output devices 1551. As previously noted, each ofthe interface modules 1420 stores a chassis control program 1840, one ormore variant control programs 1842, and an auxiliary control program1844. The interface module 1421 is associated with the chassis controlsystem 1511 and, therefore, executes a portion of the chassis controlprogram 1840. (The portion of the chassis control program 1840 executedby the interface module 1421 is determined by the location of theinterface module 1421 on the military vehicle 1410, as previouslydescribed.) The interface module 1421 executes the chassis controlprogram 1840 to determine the desired output states O-11 to O-15 basedon the I/O status information stored in the I/O status table 1520.Preferably, each interface module 1420 has complete control of its localoutput devices 1450, such that only I/O status information istransmitted on the communication network 1460 between the interfacemodules 1420.

At step 1862, the interface module 1421 controls the output devices 1551in accordance with the desired respective output states O-11 to O-15.Once the desired output state for a particular output device 1551 hasbeen determined, control is achieved by transmitting a control signal tothe particular output device 1551 by way of a dedicated communicationlink. For example, if the output is a digital output device (e.g., aheadlight controlled in on/off fashion), then the control signal isprovided by providing power to the headlight by way of the dedicatedcommunication link. Ordinarily, the actual output state and the desiredoutput state for a particular output device are the same, especially inthe case of digital output devices. However, this is not always thecase. For example, if the headlight mentioned above is burned out, theactual output state of the headlight may be “off,” even though thedesired output state of the light is “on.” Alternatively, for an analogoutput device, the desired and actual output states may be different ifthe control signal is not properly calibrated for the output device.

At step 1864, the interface module 1421 stores output status informationpertaining to the desired output states O-11 to O-15 for the outputdevices 1551 in the I/O status table 1520. This allows the output statesO-11 to O-15 to be stored prior to being broadcast on the communicationnetwork 1661. At step 1866, the interface module 1421 broadcasts theinput status information pertaining to the input states I-11 to I-15 ofthe input devices 1541 and the output status information pertaining tothe output states O-11 to O-15 of the output devices 1551 over thecommunication network 1661. The I/O status information is received bythe interface modules 1422-1425. Step 1866 is essentially the oppositeof step 1856, in which non-local I/O status information is acquired bythe interface module 1421 by way of the communication network 1661. Inother words, each interface module 1420 broadcasts its portion of theI/O status table 1520 on the communication network 1661, and monitorsthe communication network 1661 for broadcasts from the remaininginterface modules 1420 to update the I/O status table 1520 to reflectupdated I/O states for the non-local I/O devices 1441 and 1451. In thisway, each interface module 1420 is able to maintain a complete copy ofthe I/O status information for all of the I/O devices 1441 and 1451 inthe system.

The interface modules 1423 and 1425 are used to transmit I/O statusinformation between the various control systems 1511-1513. Specifically,as previously noted, the interface module 1423 is connected to both thecommunication network 1661 for the chassis control system 1511 and tothe communication network 1662 for the variant control system 1512. Theinterface module 1423 is preferably utilized to relay broadcasts of I/Ostatus information back and forth between the interface modules1421-1425 of the chassis control system 1511 and the interface modules1426-1428 of the variant control system 1512. Similarly, the interfacemodule 1425 is connected to both the communication network 1661 for thechassis control system 1511 and the to the communication network 1663for the auxiliary control system 1513, and the interface module 1425 ispreferably utilized to relay broadcasts of I/O status information backand forth between the interface modules 1421-1425 of the chassis controlsystem 1511 and the interface modules 1429-1430 of the auxiliary controlsystem 1513.

The arrangement of FIGS. 9-12 is advantageous because it provides a fastand efficient mechanism for updating the I/O status information 1848stored in the data memory 1834 of each of the interface modules 1420.Each interface module 1420 automatically receives, at regular intervals,complete I/O status updates from each of the remaining interface modules1420. There is no need to transmit data request (polling) messages anddata response messages (both of which require communication overhead) tocommunicate information pertaining to individual I/O states betweenindividual I/O modules 1420. Although more I/O status data istransmitted, the transmissions require less overhead and therefore theoverall communication bandwidth required is reduced.

This arrangement also increases system responsiveness. First, systemresponsiveness is improved because each interface module 1420 receivescurrent I/O status information automatically, before the information isactually needed. When it is determined that a particular piece of I/Ostatus information is needed, there is no need to request thatinformation from another interface module 1420 and subsequently wait forthe information to arrive via the communication network 1661. The mostcurrent I/O status information is already assumed to be stored in thelocal I/O status table 1520. Additionally, because the most recent I/Ostatus information is always available, there is no need to make apreliminary determination whether a particular piece of I/O statusinformation should be acquired. Boolean control laws or other controllaws are applied in a small number of steps based on the I/O statusinformation already stored in the I/O status table 1520. Conditionalcontrol loops designed to avoid unnecessarily acquiring I/O statusinformation are avoided and, therefore, processing time is reduced.

It may also be noted that, according to this arrangement, there is noneed to synchronize the broadcasts of the interface modules 1420. Eachinterface module 1420 monitors the communication network 1661 todetermine if the communication network 1661 is available and, if so,then the interface module broadcasts the I/O status information forlocal I/O devices 1441 and 1451. (Standard automotive communicationprotocols such as SAE J1708 or J1939 provide the ability for each memberof the network to monitor the network and broadcast when the network isavailable.) Although it is desirable that the interface modulesrebroadcast I/O status information at predetermined minimum intervals,the broadcasts may occur asynchronously.

The technique described in connection with FIGS. 9-12 also provides aneffective mechanism for detecting that an interface module 1420 has beenrendered inoperable, for example, due to damage incurred in combat. Asjust noted, the interface modules 1420 rebroadcast I/O statusinformation at predetermined minimum intervals. Each interface module1420 also monitors the amount of time elapsed since an update wasreceived from each remaining interface module 1420. Therefore, when aparticular interface module 1420 is rendered inoperable due to combatdamage, the inoperability of the interface module 1420 can be detectedby detecting the failure of the interface module 1420 to rebroadcast itsI/O status information within a predetermined amount of time.Preferably, the elapsed time required for a particular interface module1420 to be considered inoperable is several times the expected minimumrebroadcast time, so that each interface module 1420 is allowed acertain number of missed broadcasts before the interface module 1420 isconsidered inoperable. A particular interface module 1420 may beoperable and may broadcast I/O status information, but the broadcast maynot be received by the remaining interface modules 1420 due, forexample, to noise on the communication network.

This arrangement also simplifies the operation of the data logger 1485and automatically permits the data logger 1485 to store I/O statusinformation for the entire control system 1412. The data logger 1485monitors the communication network 1661 for I/O status broadcasts in thesame way as the interface modules 1420. Therefore, the data logger 1485automatically receives complete system updates and is able to storethese updates for later use.

As previously noted, in the preferred embodiment, the interface modules1423 and 1425 are used to transmit I/O status information between thevarious control systems 1511-1513. In an alternative arrangement, theinterface module 1429 which is connected to all three of thecommunication networks 1661-1663 could be utilized instead. Althoughless preferred, the interface module 1429 may be utilized to receive I/Ostatus information from each of the interface modules 1421-1428 and1430, assemble the I/O status data into an updated I/O status table, andthen rebroadcast the entire updated I/O status table 1520 to each of theremaining interface modules 1421-1428 and 1430 at periodic or aperiodicintervals. Therefore, in this embodiment, I/O status information for theall of the interface modules 1420 is routed through the interface module1429 and the interface modules 1420 acquire I/O status information fornon-local I/O devices 1440 and 1450 by way of the interface module 1429rather than directly from the remaining interface modules 1420.

From the foregoing description, a number of advantages of the preferredmilitary vehicle control system are apparent, some of which have alreadybeen mentioned. First, the control system is constructed and arrangedsuch that failure at a single location does not render the entirevehicle inoperable. The control system has the ability to dynamicallyreconfigure itself in the event that one or more interface modules arelost. By avoiding the use of a central control unit that is fixed at onelocation, and using a moving central control unit, there is no singlepoint failure. If a master interface modules fails, another interfacemodule will assume the position of the central control unit.

Additionally, because the interface modules are interchangeable, if oneinterface module is damaged, it is possible to field service the controlsystem by swapping interface modules, obtained either from within thevehicle itself or from another vehicle, even if the other vehicle is notthe same variant type. This allows the effectiveness of the militaryvehicle to be maximized by allowing undamaged interface modules to beutilized in the most optimal manner.

The use of the control system 1412 in connection with multipurposemodular vehicles is also advantageous. When the variant module ismounted to the chassis, all that is required is to connect power, groundand the communication network. Only one connector is required for all ofthe different types of variants. This avoids the need for a separateconnector on the chassis for each different type of variant module,along with the additional unutilized hardware and wiring, as hasconventionally been the approach utilized.

Moreover, since every interface module has a copy of the applicationprogram, it is possible to test each interface module as an individualunit. The ability to do subassembly testing facilitates assembly of thevehicle because defective mechanisms can be replaced before the entirevehicle is assembled.

Finally, the advantages regarding flexibility, robustness, ease of use,maintainability, and so on, that were discussed above in connection withfire fighting vehicles also apply to military vehicles. For example, itis often desirable in military applications to provide vehicles withconsoles for both a left-hand driver and a right-hand driver. Thisoption can be implemented without complex wiring arrangements with thepreferred control system, due to the distributed data collection and theintelligent processing of information from input devices. Likewise,features such as “smart start” (in which vehicle starting is controlledautomatically to reduce faulty starts due to operator error) can beimplemented by the control system without any additional hardware.

C. Electric Traction Vehicle

Referring now to FIGS. 13-17, a control system for an electric tractionvehicle 1910 is shown. An electric traction vehicle is a vehicle thatuses electricity in some form or another to provide all or part of thepropulsion power of the vehicle. This electricity can come from avariety of sources, such as stored energy devices relying on chemicalconversions (batteries), stored electrical charge devices (capacitors),stored energy devices relying on mechanical stored energy (e.g.flywheels, pressure accumulators), and energy conversion products. Ahybrid electric vehicle is an electric traction vehicle that uses morethan one sources of energy, such as one of the electrical energy storagedevices mentioned above and another source, such as an internalcombustion engine. By having more than one source of energy someoptimizations in the design can allow for more efficient powerproduction, thus one can use power from different sources to come upwith a more efficient system for traction. The disclosure herein can beused to implement electric vehicles in general and/or hybrid electricvehicles in particular. The electric vehicle 1910 can implement any ofthe other vehicle types described herein (e.g., fire fighting vehicle,military vehicle, snow blower vehicle, refuse-handling vehicle, concretemixing vehicle) as well as others not described herein. Thus, thefollowing teachings regarding the electric vehicle system may becombined with any/all of the teachings contained herein.

The electric traction vehicle 1910 preferably comprises a vehicleplatform or vehicle support structure 1912, drive wheels 1914, a powersource or principal power unit 1916, a power storage unit 1922, electricmotors 1928, servo or drive controllers 1930, an energy dissipationdevice 1932, and interface modules 1934. The vehicle 1910 furthercomprises a control system with a plurality of input and output deviceswhich vary depending on the application for which the vehicle 1920 isused. For example, if the vehicle 1910 is a fire truck, then the vehicle1910 has input and output devices such as those described in connectionwith FIGS. 1-2 in connection with the fire truck 10. Except to theextent that different I/O devices are used, the control system the sameas the control system 1412 as described in FIGS. 3-12 and is used toreceive inputs from these input devices and control these outputdevices. The interface modules 1934 are part of this control system andpreferably are constructed and operate in the same manner as theinterface modules 1420 as described above. Specifically, each interfacemodule 1934 preferably processes its own inputs and outputs based on I/Ostatus information received via I/O status broadcasts from the otherinterface modules 1934.

Interconnecting the interface modules 1934 on the electric tractionvehicle 1910 is a communication network 1976 and an AC power busassembly 1942 through which the vehicle and its various functions arecontrolled and operated. The communication network 1976 corresponds tothe communication network 60 of FIG. 2 in the case of an electric firetruck vehicle and to the communication network 1460 in the case of aelectric military vehicle. The communication network 1976 is used tocommunication I/O status information between the interface modules 1934.The AC bus assembly 1942 is a power transmission link and corresponds tothe power transmission link 102 of FIG. 2 in the case of an electricfire truck vehicle and to the power transmission link 1502 of FIG. 4 inthe case of an electric military vehicle. Also connected to the AC busassembly 1942 are the principal power unit 1916, the power storage unit1922, and the energy dissipation device 1932. The interface modules 1934include rectifier circuitry to convert AC power from the AC bus assembly1942 to DC power for output devices such as LED indicators. Also, it maybe noted that the AC power is also provided directly to the drivecontrollers 1930, which operate under the control of the interfacemodules 1934. It is also contemplated that wireless communicationbetween the interface modules 1934 and the various modules 1984 can beachieved including communication of signals 1974 via radio waves,microwaves, and fiber optical paths including relay via satellite to acentral command center.

With reference to FIGS. 20A-20B, it may be noted that manycommercially-available servo drive controllers may be network-enabledand therefore an option exists as to the manner in which the interfacemodules 1934 are connected to the drive controllers 1930. Thus, in FIG.20A, each interface module 1934 is connected to one or more drivecontrollers 1930 by way of dedicated communication links for hardwiredcontrol of the drive controllers 1930. In the illustrated embodiment,three digital links and one analog link are shown for each drivecontroller 1930 representing, for example, a stop/run output, aforward/reverse output, a generation/regeneration output, and a variabletorque command (0-100%) output from the interface module 1934. Asindicated in FIG. 13, power from the AC bus assembly 1942 is preferablyprovided directly to the drive controllers 1930 (rather than through theinterface modules 1934), and therefore each of the dedicatedcommunication links is used to transmit only information and not power.Each interface module 1934 is then connected to the communicationnetwork 1976 which, in FIG. 20A, is implemented as two separate networks(e.g., a network dedicated for use with the interface modules 1934, anda separate J1939 network to connect to the electronic control units forthe engine, transmission, anti-lock brake and central tire inflationsystems).

In FIG. 20B, each interface module 1934 is connected to one or moredrive controllers 1930 by way of a communication network for networkcontrol of the drive controllers 1930. The same information may betransmitted as in FIG. 20A except that the information is transmitted byway of the communication network. Because the AC bus assembly 1942 isconnected directly to the drive controllers 1930, there is no need totransmit power from the interface modules 1934 to the drive controllers1930. Each interface module 1934 is then connected to the communicationnetwork 1976. If only two network ports are included on the interfacemodules 1934, then information obtained from the electronic controlunits for the engine, transmission, anti-lock brake and central tireinflation systems may be obtained from other interface modules (notshown) connected to a J1939 network. Alternatively, the interfacemodules 1934 may be provided with a third network port.

The electric motors 1928 are appropriately sized traction motors. Anexemplary embodiment of an electric traction vehicle 1910 employs an AC,three phase induction electric motor having a simple cast rotor, machinemount stator and sealed ball bearings. An induction motor is preferredbecause it avoids brushes, internal switches and sliding contactdevices, with the rotor being the only moving part of the tractionmotor. Control of the electric motor 1928 is achieved by the interfacemodule 1934 through the drive controller 1930 which is coupled to themotor 1928. The torque output of the motor 1928 is adjusted based oninputs received from the operator and transmitted to the interfacemodule 1934 over the communication network 1976.

The drive wheels 1914 are rotatably mounted on the vehicle platform 1912with an electric motor 1928 coupled to at least one wheel 1914. In oneembodiment, the drive wheels 1914 are each be coupled to respectiveelectric motors 1928, which in turn are each coupled to respective drivecontrollers 1930, which in turn are coupled to respective interfacemodules 1934.

Various embodiments of an electric traction vehicle 1910 are based onthe number of wheels 1914 that are driven on the vehicle 1910. Forinstance, one embodiment includes a drive wheel 1914 coupled to anelectric motor 1928, which in turn is coupled to a drive controller1930, which in turn is coupled to an interface module 1934, which inturn is coupled to other interface modules (for other vehicle I/O) byway of the communication network 1976. The vehicle can also include fourdrive wheels 1914 coupled to four respective electric motors 1928, whichin turn are coupled to four respective drive controllers 1930, which inturn are coupled to four respective interface modules 1934, which inturn are coupled to other interface modules and to each other by way ofthe communication network 1976. In the embodiment of FIG. 1, eight drivewheels 1914 are coupled to eight respective electric motors 1928, whichin turn are coupled to eight respective drive controllers 1930, which inturn are coupled to eight respective interface modules 1934, which inturn are coupled to other interface modules and to each other by way ofthe communication network 1976. Other configurations may also be used,and the ratio of motors, wheels, servo drives and interface modules neednot be one-to-one relative to each other. Thus, for example, eachinterface module 1934 may control one wheel, one axle, a tandem set ofaxles, or other set of wheels. As described in greater detail below, thevehicle 1910 can also include pairs of drive wheels 1914 which aredriven in tandem by a respective one of the plurality of electric motors1928. Typically, at least two of the wheels are steerable.

The torque output of each motor 1928 is adjusted to meet therequirements established in the associated interface module 1934 fromthe I/O status information. The electric motors 1928 may operate toproduce electric torque to drive the drive wheels 1914 or may operate ina regenerative braking mode to provide power to the power storage unit1922, as determined by inputs received from an operator of the electrictraction vehicle 1910.

The electric traction vehicle 1910 can be configured with one or moremodular independent coil spring suspensions for steerable andnon-steerable wheel assemblies and driver and non-driver axles. Detailsof such modular independent coil spring suspensions can be found in U.S.Pat. Nos. 5,538,274, 5,820,150, and 6,105,984 incorporated herein bythis reference, which are assigned to the assignee of the presentinvention.

The principal power unit 1916 and the power storage unit 1922 aremounted on the vehicle platform 1912. As previously noted, the principalpower unit 1916 provides power for multiple electric motors 1928 coupledto individual drive wheels 1914. This simplifies the transmission ofpower to the wheels 1914 as compared to a non-electric vehicle byeliminating the torque converter, transmission, transfer case, and driveshafts. Further, because multiple electric motors 1928 are used, thehorse power requirements of each electric motor 1928 are such thatstandard commercially available electric motors may be used even in thecase of a heavy duty military vehicle.

The principal power unit 1916 includes a prime mover or engine 1918coupled to a generator or alternator 1920. The prime mover 1918 can be agas turbine or an internal combustion engine. The principal power unit1916 can also be a fuel cell or a nuclear power device. The fuel cellmay for example be a hydrogen-oxygen fuel cell that produces electricalpower in the process of a chemical reaction that combines oxygen andhydrogen to create water. If a DC source is used, an inverter may beused to convert DC power from the DC source to AC power for the AC busassembly 1942. In the preferred embodiment, the prime mover 1918 is adiesel engine optimized for operation at a constant speed (revolutionsper minute). Operating the diesel engine at a constant, optimal speedeliminates inefficiencies associated with changing RPM levels duringacceleration and deceleration, improves overall efficiency, and reducesemissions.

The generator/alternator 1920 is preferably a synchronous generatorproducing 460 to 480 volts, three phase, AC 60 Hz power for the electrictraction vehicle 1910. However, it is contemplated that different sizedgenerators or alternators can be coupled to the prime mover for purposesof generating either higher or lower electrical power. For instance, asingle phase system can be utilized or a system that generates 720 voltpower system can be used or a system that operates at a frequency otherthan 60 Hz, such as 50 Hz which is typical in European countries. It isalso contemplated that the power generated by the principal power unit1916 can be modified by appropriate auxiliary modules such as astep-down transformer to provide power to operate ancillary equipment onor associated with the electric traction vehicle 1910 such as pumps,instruments, tools, lights, and other equipment.

The AC bus assembly 1942 includes a plurality of phase conductors 1944.A first conductor 1946 having a first end 1948 and second end 1950together with a second conductor 1952 having a first end 1954 and asecond end 1956 can be configured together with a neutral 1964 toprovide single phase power in one embodiment of the vehicle 1910. Athird conductor 1958 having a first end 1960 and a second end 1962 canbe used in conjunction with the first conductor 1946 and the secondconductor 1952 to provide three phase power as shown in FIG. 1. Theconductors 1944 can be stranded metal wire such as copper or aluminumsized and clad to transmit the power generation contemplated in thevehicle 1910 design. The conductors 1944 can also be solid metal bars,generally referred to as bus bars, composed of appropriate clad metals,such as copper or aluminum, as will be appreciated by one ordinarilyskilled in the art.

Also connected to the AC power bus assembly 1942 is the power storageunit 1922, as previously mentioned. The power storage unit 1922 includesan electric power converter 1924 and an energy storage device 1926. Thepower storage unit 1922 can be configured to provide electric powerabove and beyond that required of the principal power unit 1916. Theenergy storage device 1926 can be electric capacitors, storagebatteries, a flywheel, or hydraulic accumulators. The electric powerconverter 1924 can be configured to convert the AC power generated bythe principal power unit 1916 to DC power and transfer such convertedpower to the storage device 1926. The electrical power converter 1924can also convert the energy stored in the energy storage device 1926back to AC power to augment and supplement the AC power generated by theprincipal power unit 1916 over the AC power bus assembly 1942.Applicants have determined that additional horsepower of short-termpower can be provided into the AC power bus assembly 1942 over the phaseconductors 1944 by discharge of an on-board capacitor or battery pack(energy storage device 1926) under control of the power storage unit1922. (Depending on the application, the additional power may be in therange of 100-600 or more horsepower, such as 200-300 horsepower.) In oneembodiment, the energy storage device 1926 is formed of a bank ofultracapacitors, such as the PC 500 ultracapacitor available fromMaxwell Technologies, 9244 Balboa Avenue San Diego, Calif. 92123. Thesedevices provide a high electrical energy storage and power capacity andhave the ability to deliver bursts of high power and recharge rapidlyfrom an electrical energy source/sink over hundreds of thousands ofcycles.

An advantage constructing the energy storage device 1926 of capacitorsis that capacitors are relatively easy to discharge. Therefore, it ispossible to discharge the energy storage device 1926 when maintenance isto be performed on the vehicle 1910 to avoid electrocution ofmaintenance personnel. In FIG. 13, the power storage unit 1922(including the energy storage device 1926) operates under the control ofone of the interface modules 1934. In one embodiment, the interfacemodule 1934 is used to discharge the energy storage device responsive tooperator inputs. For example, a capacitor discharge switch may beprovided in the cab of the vehicle 1910 and/or near the energy storagedevice 1926 and coupled to a nearby interface module 1934. When theoperator activates the switch, the interface modules 1934 cooperateresponsive to ensure that no electrical power is being coupled to the ACbus assembly 1942 by the generator 1920 and any other power generatingdevices, such that the energy storage device 1926 is the only powersource coupled to the AC bus assembly 1942 (e.g., when the prime moveror engine 1918 is not moving or is not coupled to the AC bus assembly1942, the generator 1920 does not provide electrical power to the AC busassembly 1942). Therefore, any stored electrical power in the energystorage device 1926 dissipates to power consuming devices that arecoupled to the AC bus assembly 1942. A variety of power consumingdevices may be provided for this purpose. For example, an energydissipation device 1932 (described in greater detail below) may be usedfor this purpose. The dissipating capacity (e.g., resistor size andpower ratings) of the energy dissipation device may be determined as afunction of the desired amount of discharge time. Other power consumingdevices already coupled to the AC bus assembly 1942, such as an enginecooling fan, may also be used. In this configuration, the interfacemodule 1934 to which the engine cooling fan is connected turns on theengine cooling fan when it is determined that the operator input at thecapacitor discharge switch has been received.

The power storage unit 1922 may be coupled to the communication network1976 and controlled by the interface module 1934. The combinedelectrical power from the principal power unit 1916 and the powerstorage unit 1922 will all be available on the AC power bus assembly1942 for use by the electric motors 1928 or by any other module 1984 orauxiliary module 1986 as determined by the operator at the userinterface 1936 of the interface module 1934.

In operation, the power storage unit 1922 receives power from theprincipal power unit 1916 over conductors 1944 of the AC power busassembly 1942. The power received is converted into the appropriateenergy mode required by the energy storage device 1926 and maintained inthe energy storage device 1926 until required during the operation ofthe vehicle 1910. If the principal power unit 1916 is not functioningfor any reason, the energy in the power storage unit can be utilized tooperate, for a given period of time, the vehicle 1910 or any of themodules 1984 or auxiliary modules 1986 mounted on the vehicle 1910. Inthe context of a military vehicle, the power storage unit 1922 may alsobe used in stealth modes of operation to avoid the noise associated withthe prime mover (e.g., diesel engine) 1918 and the generator 1920.

Energy storage recharge of the power storage unit 1922 by the principalpower unit 1916 begins automatically and immediately after the vehicle1910 arrives at its destination and continues during the vehicle'sreturn run to its original location. The state of charge of the powerstorage unit 1922 is maintained between missions by a simple plugconnection to a power receptacle in the vehicle's garage or storagelocation, which receptacle will automatically disconnect as the vehicle1910 leaves such site. The power storage unit 1922 can also receiveenergy generated by the electric motors 1928 when the motors areconfigured in a regeneration mode in which case they function as agenerator. Such functionality is utilized in a braking procedure for thevehicle as determined by the operator at a user interface 1936 (see FIG.14). The electric motor 1928 and AC power bus assembly 1942 can also beconfigured to regenerate power back to the principal power unit 1916.

As shown in FIG. 14, the vehicle 1910 can also serve as an on-site powersource for off-board electric power consuming devices 1951. For example,in the context of a military vehicle, the vehicle 1910 can serve as amobile electric generator. When the vehicle is stationary, the electricmotors 1928 consume substantially zero power. Therefore, electric powerthat would otherwise be used to drive movement of the vehicle 1910 canbe supplied to off-board equipment. In the context of an ARFF vehicle,if an airport loses electricity due to a failure in the power grid, anARFF vehicle that implements the system described herein can be used togenerate power for the airport by connecting the power bus for theairport to the AC bus assembly 1942 through the use of a suitableconnector. Likewise, at the scene of a fire, the AC bus assembly 1942can be used to provide power for scene lighting. In one preferredembodiment, the power generating capacity of the vehicle 1910 is in theneighborhood of about 500 kilowatts of electricity, which is enough topower approximately 250-300 typical homes. Depending on the size of thevehicle 1910 and the principal power unit 1916, the power generatingcapacity may be smaller (e.g., 250 kilowatts) or larger (e.g., 750kilowatts). Additionally, because the AC bus assembly 1942 provides480V, three phase, AC 60 Hz power, which is commonly used in industrialsettings, there is no need to convert the power from the AC bus assembly1942. In this regard, in FIG. 14, the off-board power-consuming devices1951 are shown not to be connected to the communication network 1976,because the power provided by the AC bus assembly 1942 can be providedto a variety of standard devices, including devices which are notspecifically designed for use with the vehicle 1910.

Preferably, an energy dissipation device 1932 is coupled to the AC busassembly 1942 and the communication network 1976. If it is determinedthat the principal power unit 1916 or the electric motors 1928 or anyother auxiliary module 1986 generating too much power or are notutilizing sufficient power, the excess power can be dissipated throughthe energy dissipation device 1932. An example of an energy dissipationdevice 1932 is a resistive coil that may be additionally cooled by fansor an appropriate fluid. Another example of an energy dissipation device1932 is a steam generator which utilizes excess heat generated in thevehicle to heat water to produce steam. Another example of an energydissipation device is to have the system back feed the generator to actas a motor and use the engine as an air pump to pull power out of thesystem. The energy dissipation device, for example, may be used duringregenerative braking when the level of charge in the capacitor bankforming the energy storage device 1926 is near its peak.

Referring now to FIG. 15, selected aspects of the vehicle 1910 of FIG.13 are shown in greater detail. The vehicle 1910 further comprises anoperator interface 1973 which includes a throttle pedal 1975, brakepedal 1977, shift control 1979, and steering wheel 1981. In FIG. 15,these input devices are shown as being connected to a common interfacemodule 1934 which is connected to the communication network 1976 alongwith the interface modules 1934 coupled to the electric motors 1928(only one of which is shown in FIG. 14). Although the input devices1975-1981 are shown as being coupled to a common same interface module,the input devices may also be coupled to different interface modules.The operator interface may also receive inputs from other input devicesto raise or lower the vehicle, lock the suspension, control aload-handling system, and control vehicle operation in stealth modes ofoperation (e.g., operating exclusively on the power storage unit 1922).The operator interface 1973 may include a display that displaysinformation to the operator such as speed, charge level of the storageunit 1922, generator efficiency, direction of travel, alarm status, fueleconomy, temperatures, pressures, and data logging information.

Each interface module 1934 receives the I/O status information from theoperator interface 1973. For those interface modules that are connectedto a respective drive controller 1930 and electric motor 1928, the I/Ostatus information from the operator interface 1973 is processed toprovide control signals to control the electric motor 1928. This processis shown in FIG. 15.

Referring now to FIG. 16, at step 2010, throttle, brake, shift, andsteering inputs are received from the operator at the interface module1934 which is connected to the operator interface 1973. At step 2012,the throttle, brake, shift and steering inputs are transmitted by way ofthe communication network 1976 (during I/O status broadcasts aspreviously described). At step 2014, this information is received ateach of the remaining interface modules 1934. At step 2016, theinterface modules 1934 that control the electric motors 1928 use thethrottle, brake, shift and steering inputs to control the electricmotors 1928. To this end, the interface modules 1934 determine a speedor torque command and provide this command to the drive controller 1930.Other information, such as vehicle weight, minimum desired wheel speed,wheel slip control parameters, and other information may also be used.Although the vehicle 1910 does not include a mechanical transmission,the shift input from the shift input device 1979 may be used to causethe electric motors 1928 to operate at different operating pointsdepending on a status of the shift input device, with each of theoperating points corresponding to different torque productioncapabilities (or different tradeoffs between vehicleresponsiveness/acceleration capability and motor efficiency).

Each interface module 1934 preferably includes a number of controlsubprograms, including a subprogram 1983 for differential speed control,a subprogram 1985 for regenerative brake control, a subprogram 1987 forefficiency optimization control, and a configuration interface 1989.These programs provide for further control of the torque/speed commandgiven by each interface module 1934 to the respective drive controller1930.

The differential speed control program 1987 accepts the steering angleas an input and controls the motor speed of each motor 1928 such thatthe wheels 1914 rotate at slightly different speeds during vehicleturning maneuvers. The differential speed control program 1987 is anelectronic implementation of a mechanical differential assembly. Thesteering angle input may also be used by another interface module 1934to control a steering mechanism of the vehicle 1910 to thereby control adirection of travel of the vehicle 1910. Preferably, steering controltakes into account other I/O status information (such as vehicle speed)and is optimized to avoid vehicle slippage (“scrubbing”) during turnmaneuvers. The differential speed control program 1987 monitors motortorque output along with other system parameters such that the speeddifference between motors does not go above a predefined limit. This canbe controlled both side by side and front to back and combinations ofboth. By commanding torque and monitoring and adjusting for speeddifference, optimal tractive force can be put to ground in any tractioncondition.

Regenerative brake control program 85 controls the motor 1928 such thatthe motor provides a braking action to brake the vehicle 1910 inresponse a regeneration/auxiliary signal is received. For example, asignal may be received from a brake pedal request (the brake pedal 1977is pressed), no TPS count, or other user controlled input/switch. Thiscauses the motor 1928 to act as a generator to regenerate power back tothe power storage unit 1922 or the principal power unit 1916 via the ACbus assembly 1942. In addition to regenerative braking, a standardanti-lock brake system is also used.

The efficiency optimization control program 87 controls motor speed andtorque conditions to allow a first subset of the motors 1928 to operateat an optimal power for a particular speed, and a second subset of themotors 1928 to operate in a regenerative mode. Having one set of motorsoperate 1928 at an optimal power for a particular speed and a second setof motors 1928 operate in a regenerative mode is more efficient anddraws less net power than having all of the motors 1928 operating at anon-optimal speed. Alternative power matching schemes may also be usedin which optimum efficiency for some of the motors 1928 is reached byhaving some of the remaining motors 1928 operate in a non-torqueproducing mode.

Configuration interface program 1989 allows for reconfiguration of thevehicle 1910 depending on which types of auxiliary modules are mountedto the vehicle 1910. The configuration program 1989 detects what type ofauxiliary modules are connected to the vehicle, and adjusts theconfiguration of the control program executed by the interface modules1934 to take into account the particular configuration of the vehicle1910 as determined by which auxiliary modules are present.

In particular, in the preferred embodiment, the principal power unit1916, the power storage unit 1922, and the energy dissipation device1932 are provided as auxiliary modules 1984 that are removably mountedon the vehicle platform and are removably connected to the communicationnetwork 1976 and the AC bus assembly 1942 by way of a suitable connectorassembly. Other auxiliary modules 1986 may also be provided. Anauxiliary module 1986 can be any type of equipment or tool required orassociated with the function and operation of the vehicle 1910. Forexample, the auxiliary module can be a pump, a saw, a drill, a light,etc. The auxiliary module 1986 is removably connected to thecommunication network 1976 and the AC bus assembly 1942. A junction 1988is used to facilitate the connection of the modules to the communicationnetwork 1976 and the AC power bus assembly 1942 and multiple junctions1988 are located at convenient locations throughout the vehicle 1910.The junctions 1988 can accommodate various types of connections such asquick connectors, nuts and bolts, solder terminals, or clip terminals orthe like. The junction 1988 can include a connector to accommodateconnection to the communication network 1976 and/or the AC bus assembly1942. Additional auxiliary modules can be added to the vehicle 1910 ascircumstances and situations warrant.

In the preferred embodiment, and as shown in FIG. 17, auxiliary drivemodules 1953 are used that each include a respective one of the drivewheels 1914, a respective one of the electric motors 1928, a respectiveone of the drive controllers 1930, and a respective one of the interfacemodules 1934. Like the other auxiliary modules discussed above, theauxiliary drive modules 1953 are capable of being removed, replaced, andadded to the vehicle 1910. To this end, each auxiliary drive moduleincludes an electrical connector that mates with a compatible electricalconnector one the vehicle platform 1912 and a mechanical mounting system(e.g., a series of bolts) that allows the auxiliary drive module 1953 tobe quickly mounted to or removed from the vehicle 1910. The electricalconnector connects the interface module 1934 to a communication network1976 and connects the drive controller 1930 to the AC bus assembly 1942.Therefore, if one auxiliary drive module 1953 malfunctions, theauxiliary drive module 1953 can be removed and replaced with a properlyfunctioning auxiliary drive module 1953. This allows the vehicle 1910 toreturn immediately to service while the inoperable drive module isserviced. This arrangement also allows the same vehicle to be providedwith different drive capacities depending on intended usage. Forexample, under one usage profile, the vehicle 1910 may be provided withfour auxiliary drive modules 1953. Under a second usage profile, thevehicle 1910 may be provided with two additional auxiliary drive modules1953′ for extra drive capacity. Additionally, the vehicle platform 1912is preferably a generic vehicle platform that is used with severaldifferent types of vehicles having different application profilesrequiring different drive capacities. In this regard, it may also benoted that the principal power unit 1916 is also capable of beingremoved and replaced with a principal power unit 1916 with a largerelectric generation capacity. This feature is therefore advantageous inthat auxiliary drive modules 1953 are capable of being added to andremoved from the vehicle as a unit to achieve a corresponding increaseor decrease in the drive capacity of the vehicle 1910, thereby givingthe vehicle 1910 a reconfigurable drive capacity. As previouslyindicated, the system can be configured to have one of the interfacemodules 1934 control a single drive wheel 1914, an entire axle assembly(one or two motor configuration) as well as a tandem axle assembly (oneand two motor axle configurations), as well as other permutations andcombinations.

Referring to FIG. 16, FIG. 16 shows the operation of the configurationprogram 1989. At step 2020, it is detected that there has been a changein vehicle configuration. The auxiliary module may be any of theauxiliary modules described above. Step 2020 comprises detecting that anauxiliary module has been added in the case of an added auxiliarymodule, and comprises detecting that an auxiliary module has beenremoved in the case of a removed auxiliary module. If an auxiliarymodule has been rendered in operable (e.g., one of the electric motors1928 has failed), then step 2020 comprises detecting that the inoperableauxiliary module has failed.

At step 2022, the configuration change is characterized. For example, ifan auxiliary module has been added or removed, the type and location ofthe added/removed auxiliary module is determined. If one auxiliarymodule has been replaced with another auxiliary module, the location atwhich the change was made as well as the module type of the added andremoved auxiliary modules is determined. In the case where the auxiliarymodule comprises an interface module 1934, the different characteristicsof the different auxiliary modules may be stored in the respectiveinterface modules 1934. As a result, step 2022 may be performed byquerying the interface module 1934 of the removed auxiliary module(before it is removed) and by querying the interface module of the addedauxiliary module.

At step 2024, the vehicle 1910 is reconfigured to accommodate the addedauxiliary drive module. Step 2024 comprises updating control algorithmsin the interface modules 1934. For example, if two auxiliary drivemodules are added, the control algorithms may be updated to decrease thehorsepower produced by the original motors 1928 in response to aparticular throttle input to take into account the additional horsepowerprovided by the added electric motors 1928. Alternatively, if one of theelectric motors 1928 fails or is otherwise rendered inoperable, then theupdating compensates for less than all drive wheels being driven bycausing the remaining electric motors to be controlled to provideadditional horsepower. This gives the vehicle 1910 different modes ofoperation, for example, a first mode of operation in which the electricmotors are controlled such that all of the plurality of drive wheels aredriven, and a second mode of operation in which the electric motors arecontrolled such that less than all of the plurality of drive wheels aredriven.

At step 2026, a confirmation is sent to the operator of the vehicle 1910via a display of the operator interface 1973 to confirm that the vehiclehas been reconfigured. It may also be desirable to transmit thisinformation to other systems. For example, one of the interface modules1934 may be provided with a wireless modem, and the change inconfiguration information may be transmitted wireless to an off-boardcomputer using a radio frequency (RF) communication link. Indeed, any ofthe information stored in any of the interface modules or any of theother vehicle computers (e.g., engine control system, transmissioncontrol system, and so on) may be transmitted to an off-board computersystem in this manner to allow off-board vehicle monitoring and/oroff-board vehicle troubleshooting. The transfer of information may occurthrough a direct modem link with the off-board vehicle computer orthrough an Internet connection.

Thus, the vehicle 1910 has a modular construction, with the principalpower unit 1916, the power storage unit 1922, the energy dissipationdevice 1932, the auxiliary drive modules 1953, other drive modules 1984and 1986, and so on, being provided as modules that can be easily addedto or removed from the vehicle. Any number of such modules can be addedand is limited only by the extent to which suitable locations whichconnections to the communication network and AC bus assembly 1942 existon the vehicle 1910. Once such a device is added, the control system isautomatically reconfigured by the interface modules 1934.

FIG. 13 illustrates the wheels 1914 being driven directly by an electricmotor 1928 through an appropriate wheel-end reduction assembly 1982 ifnecessary. Referring now to FIGS. 19A-19B, a wheel-end reductionassembly 1982 can also couple the wheels 1914 to a differential assembly1978 via drive shafts. A plurality of wheel-end reduction assemblies1982 can couple the wheels 1914 to their respective electric motors1928. Another embodiment of the vehicle 1910 includes a differentialassembly 1978 coupled to the electric motor 1928 for driving at leasttwo wheels 1914 as shown in FIG. 15. Additional differential assemblies1978, such as three assemblies 1978, with each differential assemblycoupled to an electric motor 1928 for driving at least two wheels, canalso be configured in the vehicle 1910.

Referring now to FIG. 21, a method of transferring data indicative of anelectric traction vehicle 1910 to potential customers over the Internet1992 includes obtaining information on an electric traction vehicle 1910including dates, prices, shipping times, shipping locations, generalshipping data, module type, inventory, specification information,graphics, source data, trademarks, certification marks and combinationsthereof. The method further includes entering the information on to aterminal 1990 that is operationally connected to an Internet server.Terminal 1990 may be microprocessor, a computer, or other conventionallyknown device capable of operationally connecting to a conventionallyknown Internet server. The method further includes transmitting to theinformation from terminal 1990 to the Internet server that isoperationally connected to Internet 1992. Information be transmitted tothe internet from the interface modules 1934 and may include any of theinformation stored in the interface modules 1934 or any other vehiclecomputer, as previously noted. The method allows manufacturers 1994,distributors 1996, retailers 1997 and customers 1998, throughout the useof terminals 1990, to transmit information, regarding the electrictraction vehicle 1910 and the potential sale of the electric tractionvehicle 1910 to customers, to one another individually, collectively orby any combination thereof.

Thus, there is provided an electric traction vehicle of modular designwith the modules interconnected by an AC bus assembly and a data busnetwork. Other embodiments using other types of vehicles are possible.For example, an electric traction vehicle using a modular componentdesign can be utilized as a fire truck for use at an airport or one thatcan negotiate severe off-road terrain. The vehicle can also be used in amilitary configuration with the ability to negotiate extreme side slopesand negotiate extreme maneuvers at high speeds. The modular aspect ofthe vehicle architecture will allow for optimum placement of componentsto maximize performance with regard to center of gravity which willfacilitate its operational capabilities.

D. Network Assisted Monitoring, Service, and Repair

Referring now to FIG. 22, a preferred embodiment of an equipment servicevehicle 210 having a diagnostic system 212 according to an embodiment ofthe invention is illustrated. By way of overview, the diagnostic system212 comprises an intelligent display module 214, a test interface module221 connected to a plurality of sensors 222, and a plurality ofadditional vehicle control systems 224-230. The intelligent displaymodule 214, the test interface module 221, and the plurality ofadditional vehicle control systems 224-230 are interconnected with eachother by way of a communication network 232.

More specifically, the vehicle 210 is a military vehicle and, inparticular, a medium tactical vehicle. However, it should be understoodthat the diagnostic system 212 of FIG. 22 could also be used with othertypes of military vehicles. For example, the diagnostic system 212 couldbe used in connection with heavy equipment transporter vehicles, whichare used to transport battle tanks, fighting and recovery vehicles,self-propelled howitzers, construction equipment and other types ofequipment. These types of vehicles are useable on primary, secondary,and unimproved roads and trails, and are able to transport in excess of100,000 pounds or even in the range of 200,000 pounds or more. Thediagnostic system 212 can also be used in connection with palletizedload transport vehicles, in which a mobile truck and trailer form aself-contained system capable of loading and unloading a wide range ofcargo without the need for forklifts or other material handlingequipment. Such trucks are provided with a demountable cargo bed and ahydraulically powered arm with a hook that lifts the cargo bed on or offthe truck. These trucks may be also provided with a crane to drop offthe pallets individually if the entire load is not needed. Further, thediagnostic system 212 can also be used in connection with trucksdesigned for carrying payloads for cross country military missions. Suchtrucks may include, for example, cargo trucks, tractors, fuel servicingtrucks, portable water trucks, and recovery vehicles (with crane andwinch). Such trucks are capable of passing through water crossings threeor four or more feet deep. These trucks can also be used for missiletransports/launchers, resupply of fueled artillery ammunition andforward area rearm vehicles, refueling of tracked and wheeled vehiclesand helicopters, and recovery of disabled wheeled and tracked vehicles.The diagnostic system 212 can be used in connection with a wide range ofother military vehicles as well.

The intelligent display module 214 provides an operator interface to thediagnostic system 212 and also provides intelligence used to conductdiagnostic tests and other services. In particular, the intelligentdisplay module 214 includes a test control module 215 (which furtherincludes a microprocessor 216 and a diagnostic program 217) and anoperator interface 218 (which further includes a display 219 and akeypad 220) (see FIG. 23).

In the preferred embodiment, the test control module 215 and theoperator interface 218 are provided as a single, integrated unit(namely, the intelligent display module 214) and share the same housingas well as at least some of the internal electronics. Other arrangementsare possible, however. For example, as can be easily imagined, it wouldalso be possible to provide the test control module 215 and the operatorinterface 218 in the form of separate physical units, although thisarrangement is not preferred for reasons of increased cost and partscount. Both the test control module 215 and the operator interface 218can be obtained in the form of a single, integrated unit from AdvancedTechnology, Inc., Elkhart, Ind. 46517. This product provides a genericflat panel 4 line×20 character display 219, four button keypad 220,microprocessor 216, and memory that is capable of being programmed witha program (such as the diagnostic program 217) to customize theintelligent display module for a particular application. Of course, amore (or less) elaborate intelligent display module could also beutilized. For example, if on-line parts ordering capability isincorporated as detailed below, then a display module with an SVGA flattouch screen monitor with a microprocessor and memory may be preferred.Also, the test control module 215 may be implemented using one of theinterface modules 20, 30, 1420 previously described, providing that theinterface module has sufficient graphics capability to drive a display.

Also in the preferred embodiment, the intelligent display module 214 issemi-permanently mounted within the vehicle 210. By semi-permanentlymounted, it is meant that the intelligent display module 214 is mountedwithin the vehicle 210 in a manner that is sufficiently rugged towithstand normal operation of the vehicle for extended periods of time(at least days or weeks) and still remain operational. However, that isnot to say that the intelligent display module 214 is mounted such thatit can never be removed (e.g., for servicing of the intelligent displaymodule) without significantly degrading the structural integrity of themounting structure employed to mount the intelligent display module 214to the remainder of the vehicle 210. The intelligent display module 214is preferably mounted in an operator compartment of the vehicle 210, forexample, in a storage compartment within the operator compartment or onan operator panel provided on the dashboard.

The operation of the test control module 215, and in particular of themicroprocessor 216 to execute the diagnostic program 217, is shown anddescribed in greater detail below in conjunction with the flowchart ofFIG. 25. In general, the microprocessor 216 executes the diagnosticprogram 217 to diagnose subsystem faults, to display fault information,to maintain vehicle maintenance records, and to perform data logging forsystem diagnosis and/or for accident reconstruction. Depending on theapplication, it may be desirable to incorporate additional services aswell, or to incorporate fewer than all of these services.

The operator interface 218 includes the display 219 which is used tocommunicate (and, in particular, to display) information to theoperator. For example, the display 219 is used to prompt the operator toenter information into the keypad 220, or to take certain actions withrespect to the vehicle during testing (e.g., bring the engine to aspecified RPM level). The display 219 is also used to display a menu orseries of menus to allow the operator to select a test to be performedor to select another service of the intelligent display module 214 to beutilized. The display 219 is also used to display status informationduring system startup and during testing, and to display any errormessages that arise during system startup or during testing. The display219 is also used to display input data and fault mode indicators fromcontrol systems 224-230, and any other information from additionalvehicle subsystems. The display 219 is also used to display informationfrom discrete sensors such as the sensors 222. The display 219 is alsoused to display the results of diagnostic tests that are performed(e.g., a pass/fail message or other message).

Preferably, the display 219 displays all of this information to theoperator in a user-friendly format as opposed to in the form of codesthat must be interpreted by reference to a separate test or servicemanual. This is achieved in straightforward fashion by storing in thememory of the intelligent display module 214 information of the typecommonly published in such manuals to facilitate manual interpretationof such codes, and using this information to perform the translationautomatically. Likewise, as previously noted, the display 219 is used toprompt the operator to take certain actions with respect to the vehicleduring testing and to otherwise step the operator through any testprocedures, without reference to a test manual. This allows the amountof operator training to be reduced.

The operator interface 218 also includes the keypad 220 which is used toaccept or receive operator inputs. For example, the keypad 220 is usedto allow the user to scroll through and otherwise navigate menusdisplayed by the display 219 (e.g., menus of possible tests to beperformed on the vehicle 210), and to select menu items from thosemenus.

As previously noted, it would also be possible to utilize a moreelaborate intelligent display module. For example, a more elaboratekeypad 220 could be utilized if more data entry capability is desired.In this regard, however, it is noted that the intelligent display module214 also preferably includes a communication port that allows thedisplay module to communicate with a personal computer 233 by way of acommunication network 232 (see FIG. 23). The personal computer 233 canbe used to retrieve, manipulate and examine data stored within theintelligent display module 214. For example, if the intelligent displaymodule 214 includes a data logger as described below, the personalcomputer can be used to retrieve and examine the information stored bythe data logger. Likewise, if the intelligent display module 214implements a vehicle maintenance jacket, the personal computer 233 canbe used to retrieve and modify data stored in the vehicle maintenancejacket. Further, using the personal computer 233, it is possible tointegrate the diagnostic system 212 with an interactive electronictechnical manual (IETM), to allow the interactive electronic technicalmanual to access the data available from the diagnostic system 212.

The test interface module 221 accepts requests from the intelligentdisplay module 214 for information from the sensors 222, retrieves therequested information from the respective sensor 222, converts inputsignals from the respective sensor 222 into a format that is compatiblewith the communication network 232, and transmits the information fromthe respective sensor 222 to the intelligent display module 214 via thecommunication network 232. The test interface module 221 is thereforeimplemented as a passive unit with no standard broadcasts that burdenthe communication network 232. As a result, in operation, the testinterface module 221 does not regularly transmit data on thecommunication network 232. Rather, the test interface module 221passively monitors the communication network 232 for informationrequests directed to the interface module 221. When an informationrequest is received, the test interface module 221 obtains the requestedinformation from the relevant sensor 222, and then transmits therequested information on the communication network 232 to theintelligent display module 214. Alternatively, in accordance with thearrangement described in FIGS. 9-12, it may be desirable to implementthe test interface module 221 as an active unit that broadcasts inputstatus information in the same manner as the interface modules 1420.

The test interface module 221 may, for example, include as many inputsas there are sensors 222. Each input may include associated switches forconfiguring the input, an analog-to-digital converter to convert analogsignals to a digital format, and any other signal processing circuitry.The number of inputs is not important, since it is possible to use fewertest interface modules each with a larger number of inputs, or more testinterface modules each with a smaller number of inputs. The number ofinputs is not limited in any particular way and is determined by need.

In practice, the test interface module 221 may be a commerciallyavailable unit capable of putting information from discrete sensors ontoa communication network such as SAE (Society of Automotive Engineers)J1708. The test interface module 221 preferably also meets applicablestandards for underhood installation, such as SAE J1455, to allow thetest interface module to be located in close proximity to the sensors222 to reduce wiring. The test interface module may, for example, beobtained from Advanced Technology Inc., Elkhart, Ind. 46517 (PN3246282). Again, however, a wide range of devices of varyingconstruction and complexity could be utilized to implement the testinterface module 221.

The test interface module 221 is connected to the plurality of sensors222 which are each capable of obtaining information pertaining to thehealth and operation of a vehicle subsystem. “Health” and “operation”are interrelated and information that pertains to one will, at least tosome extent, pertain to the other as well. The sensors 222 are discretesensors in the sense that they are not integrally provided with thecontrol systems 224-230 and associated controlled mechanical systems(e.g., engine, transmission, and so on) 234-240. The sensors are add-ondevices that are used only in connection with the intelligent displaymodule 214. In general, discrete sensors are preferably only used whenthe information provided by the sensor is not otherwise available on thecommunication network 232. In FIG. 23, the sensors 222 are shown toinclude a fuel filter inlet pressure sensor 222 a, fuel pump outletpressure sensor 222 b, fuel return pressure sensor 222 c, oil filtersensors 222 d, an air cleaner pressure sensor 222 e, a fuel differentialpressure switch 222 f, and a shunt resistor 222 g (used to determinecompression imbalance based on unequal current peaks in the startercurrent).

In addition to the intelligent display module 214 and the test interfacemodule 221, the diagnostic system 212 also includes a plurality ofadditional vehicle control systems 224-230, as previously noted. Asshown in FIG. 23, the control system 240 is a central tire inflationcontrol system that controls a central tire inflation system (CTIS) 34,the control system 226 is an anti-lock brake control system thatcontrols an anti-lock brake system (ABS) 236, the control system 228 isa transmission control system that controls a transmission 238, and thecontrol system 230 is an engine control system that controls an engine240. The vehicle subsystems formed by the mechanical systems 234-240 andassociated control systems 224-230 are conventional and are chosen inaccordance with the intended use of the vehicle 210.

The control systems 224-230 each store information pertaining to thehealth and operation of a respective controlled system. The controlsystems 224-230 are capable of being queried and, in response, makingthe requested information available on the communication network 232.Because the vast amount of information required for performing mostdiagnostic tests of interest is available from the control systems224-230 by way of the communication network 232, it is possible todrastically reduce the number of discrete sensors 222 that are required.Thus, as just noted, discrete sensors are preferably only used when theinformation provided by the sensor is not otherwise available on thecommunication network 232.

Typically, each of the control systems 224-230 comprises amicroprocessor-based electronic control unit (ECU) that is connected tothe communication network 232. When the intelligent display module 214requires status information pertaining to one of the mechanical systems234-240, the intelligent display module 214 issues a request for theinformation to the respective one of the control systems 224-230. Therespective control system then responds by making the requestedinformation available on the communication network 232.

Typical ECUs for transmission and engine control systems are capable ofproducing fault codes and transmitting the fault codes on thecommunication network 232. Depending on the type of fault, the faultcodes may be transmitted automatically or alternative only in responseto a specific request for fault information. Typical ECUs for centraltire inflation systems and anti-lock brake systems also transmit faultcodes but, in most commercially available systems, fault codes aretransmitted only in response to specific requests for fault information.When a fault code is transmitted on the communication network 232, theintelligent display module 214 receives the fault codes from thecommunication network 232, interprets the fault codes, and displays theinterpreted fault codes to a human operator using the display 219.

It may be noted that the diagnostic system 212 may be implemented as astand-alone system or in the context of the control systems 12 and 1412described in connection with FIGS. 1-12. For example, in the context ofthe control system 1412, the communication network 232 and thecommunication network 1460 may be the same network, such that theintelligent display module 214 and the test interface module 221 aredisposed on the communication network 1460 along with the interfacemodules 1420. When combined in this manner, the anti-lock brake controlsystem 226 and anti-lock brake control system 1495 are in practice thesame devices, as are the transmission control system 228 and thetransmission control system 1493, and the engine control system 230 andthe engine control system 1491, and also as are the respectivecontrolled subsystems. The intelligent display module 214 maintains adynamically updated I/O status table 1520 by listening to the I/O statusbroadcasts made by the interface modules 1420 and the control systems224-230, as described in connection with FIGS. 9-12. This makes itpossible to connect the sensors 222 to the communication network 232 byway of one or more of the interface modules 1420 rather than through theuse of a separate dedicated test interface module, and making itpossible to eliminate redundant sensors. A further advantage of thisarrangement is that the intelligent display module 214 has access to allof the I/O status information provided by the interface modules 1420.

Referring now to FIG. 24, in general, during operation, the display 219displays menus to the operator and the keypad receives operator inputsused to navigate the menu, make menu selections, and begin testing.Assuming other services are also provided, the operator is firstprompted to select an option from among a list of options that includesoptions of other services provided by the intelligent display module214. The list of options may include, for example, an option 250 toperform vehicle diagnostic testing, an option 252 to view engine codes,an option 254 to view transmission codes, an option 256 to view ABScodes, an option 258 to view CTIS codes, an option 260 to view and/ormodify data in the vehicle maintenance jacket, and an option 262 to viewinformation stored in a data logger. Given that the display 219 is afour line display in the preferred embodiment, a vertically slidingwinding 264 is used to scroll through the options, and the user pressesa select button on the keypad 220 when a cursor 266 is positioned on thedesired option. As previously noted, other options may also be provided.

Referring now to FIG. 25, a flowchart showing the operation of thediagnostic system of FIGS. 22-23 to perform a diagnostic test isillustrated. In connection with military vehicles, the diagnostic system212 may for example be made capable of performing the followingdiagnostic tests, all of which provide information pertaining to thehealth and operation of the tested subsystem:

Exemplary Test Description and Measurement Test Application Range(s)ENGINE TESTS Engine RPM Measures average speed of  50-5000 RPM (AVE)engine crankshaft. Engine RPM, Measures cranking RPM.  50-1500 RPMCranking SI only Performed with ignition ON. Inhibit spark plug firingallowing cranking without starting. Power Test Measures engine's power500-3500 RPM/s (RPM/SEC) producing potential in units of RPM/SEC. Usedwhen programmed engine constants and corresponding VehicleIdentification Number (VID) have not been established. Power TestMeasures percentage of  0-100% (% Power) engine's power producingpotential compared to full power of a new engine. Compression Evaluatesrelative cylinder  0-90% Unbalance (%) compression and displays percentdifference between the highest and the lowest compression values in anengine cycle. IGNITION TESTS Dwell Angle Measures number of degrees 10-72 @ 2000 (TDC) that the points are closed. RPM Points VoltageMeasures voltage drop across  0-2 VDC (VDC) the points (points positiveto battery return). Coil Primary Measures voltage available at  0-32 VDCthe coil positive terminal of the operating condition of the coil.FUEL/AIR SYSTEM TESTS Fuel Supply  0-100 psi Pressure (psi) Fuel SupplyThis test measures the outlet  0-10 psi Pressure (psi) pressure of thefuel pump.  0-30 psi  0-100 psi  0-300 psi Fuel Return Measures returnpressure to  0-100 psi Pressure (psi) detect return line blockage,leaks, or insufficient restrictor back pressure. Fuel Filter Detectsclogging via opening of PASS/FAIL Pressure Drop a differential pressureswitch (PASS/FAIL) across the secondary fuel filter. Fuel SolenoidMeasures the voltage present at  0-32 VDC Voltage (VDC) the fuel shutoffsolenoid positive terminal. Air Cleaner Measures suction vacuum in air 0-60 in. H₂O Pressure Drop intake after the air cleaner (RIGHT)relative to ambient air pressure (In H₂O) to detect extent of aircleaner clogging. Air Cleaner Second air cleaner on dual  0-60 in. H₂OPressure Drop intake systems. (LEFT) (In H₂O) Turbocharger Measuresdischarge pressure of  0-50 in. Hg Outlet Pressure the turbocharger.(RIGHT) (In Hg) Turbocharger Second turbocharger on dual  0-50 in. HgOutlet Pressure intake systems. (LEFT) (In Hg) Airbox Pressure Measuresthe airbox pressure of  0-20 in. Hg (In Hg) two stroke engines. This 0-50 in. Hg measurement is useful in detecting air induction pathobstructions or leaks. Intake Manifold Spark ignition engine intake 0-30 in. Hg Vacuum (In Hg) system evaluation. Intake Manifold Sparkignition engine intake  0-30 in. Hg Vacuum Varia- system evaluation.tion (In Hg) LUBRICATION/COOLING SYSTEM TESTS Engine Oil Measures engineoil pressure.  0-100 psi Pressure (psi) Engine Oil Filter Measures thepressure drop  0-25 psi across the engine oil filter as

Exemplary Test Description and Measurement Test Application Range(s)indicator of filter element clogging. Engine Oil Primarily applicable toair cooled   120-300° F. Temperature engines. Requires transducer (° F.)output shorting switch on vehicle to perform system zero offset test.Engine Coolant Transducer output shorting   120-300° F. Temperatureswitch on vehicle required. (° F.) STARTING/CHARGING SYSTEM TESTSBattery Voltage Measure battery voltage at or    0-32 VDC (VDC) nearbattery terminals. Starter Motor Measures the voltage present at    0-32VDC Voltage (VDC) the starter motor positive terminal. Starter NegativeMeasures voltage drop on    0-2 VDC Cable Voltage starter path. A highvoltage Drop (VDC) indicates excessive ground path resistance. StarterSolenoid Measures voltage present at the    0-32 VDC Volts (VDC) startersolenoid's positive terminal. Measures current through battery groundpath shunt. Starter Current, Measures starter current.    0-1000 AAverage (amps)    0-2000 A Starter Current Provides a good overall   0-1000 A First Peak (Peak assessment of complete    0-2000 A Amps,DC) starting system. Tests condition of the starting circuit andbattery's ability to deliver starting current. The measurement is madeat the moment the starter is engaged and prior to armature movement.Peak currents less than nominal indicate relatively high resistancecaused by poor connections, faulty wiring, or low battery voltage.Battery Internal Evaluate battery condition by    0-999.9 Resistancemeasuring battery voltage and mohm (Milliohms) current simultaneously.Starter Circuit Measures the combined    0-999.9 Resistance resistanceof the starter circuit mohm (Milliohms) internal to the batteries.Battery Resist- Measures rate of change of    0-999.9 ance Changebattery resistance as an mohm/s (Milliohms/sec) indicator of batterycondition. Battery Current Measures current to or from the −999-1000 Abattery. −999-2000 A Battery Electro- Determines whether electrolytePASS/FAIL lyte Level in the sensed cell is of sufficient (PASS/FAIL)level (i.e., in contact with electrolyte probe). Alternator/Gener-Measures output voltage of    0-32 VDC ator Output generator/alternator.Voltage (VDC) Alternator/Gener- Measures voltage present at    0-32 VDCator Field Voltage alternator/generator field (VDC) windings.Alternator/Gener- Measures voltage drop in    0-2 VDC ator Negativeground cable and connection Cable Voltage between alternator/generatorDrop (VDC) ground terminal and battery negative terminal. AlternatorOutput Measures voltage output at the    0-3 VAC Current Sense currenttransformer in 650 (VAC-RMS) ampere alternator. Alternator Measuresalternator output    0-22 VAC AC Voltage voltage. Sense (VAC-RMS)

In general, the specific diagnostic tests that are performed will beselected depending on the application, including the type of equipmentutilized by the vehicle 210. Most or all tests may be simple in naturefrom a data acquisition standpoint, involving primarily bringing thevehicle to a particular operating condition (e.g., engine speed), ifnecessary, and obtaining information from a suitable transducerconstructed and placed to measure the parameter of interest, althoughmore elaborate tests could also be utilized. Any number of differentvehicle parameters can be measured, each providing a separate data pointregarding the operational health of the vehicle. By providing anoperator with enough data points regarding the operational health of thevehicle, the operator can use this information in a known way todetermine whether the vehicle is in good working order, or whether somesubsystem or component thereof needs to be repaired or replaced.

At step 302, once the vehicle diagnostic option is selected, the display219 displays a menu of various tests that are available to the operator,and the operator is prompted to select a test from the test menu. Again,the list of options may comprise dozens of options, such as some or allof those listed above, and/or tests other than those listed above, andthe operator can scroll through the menu and selected the desiredoption.

At Step 304, the operator is prompted to perform a vehicle relatedaction. This step, which may or may not be necessary depending on thetype of test performed, may be used to prompt the operator to start theengine to develop fuel pressure, oil pressure, and so on, depending onwhich vehicle parameter is tested. For example, if it is desired to testthe operational health of the battery, then the operator may be promptedto engage the starter for a predetermined amount of time to establish acurrent draw on the battery.

At Step 306, the intelligent display module 214 issues a request forinformation from the test interface module 221 and/or from one or moreof the control systems 224-230. As previously noted, the test interfacemodule 221 does not continually broadcast information on thecommunication network 232, because the sensors 222 connected to the testinterface module are used only for diagnostic testing and becausepresumably diagnostic testing will be performed only infrequently.Therefore, when the intelligent display module 214 needs informationfrom one of the sensors 222 pursuant to a test requested to be performedby the operator at the operator interface 218, the intelligent displaymodule 214 requests the test interface module 221 for this information.

Alternatively, the needed information may be of a type that is availablefrom one of the control systems 224-230. The control systems 224-230 arenot only able to acquire information from sensors located within thesystems 234-240, but are also able to maintain information derived fromsensors located within the systems 234-240. For example, the enginecontrol system 230 may maintain information pertaining to the averageRPM of the engine, which is a parameter that is not directly measurablebut that can be easily calculated based on parameters that are directlymeasurable. Through the communication network 232, all of thisinformation is made available to the diagnostic system 212. When theintelligent display module 214 needs information from one of the controlsystems 224-230 pursuant to a test requested to be performed by theoperator at the operator interface 218, the intelligent display module214 requests the respective control system for this information.

At Step 308, the requested information is retrieved from one of thesensors 222 by the test interface module 221, or from memory or aninternal sensor by the respective control system 224-230. At step 309,the information is transmitted from the test interface module 221 orfrom one of the control systems 224-230 to the intelligent displaymodule 214 by way of the communication network 232.

Alternatively, the needed information may be of a type that is availablefrom one of the interface modules 1420. In this case, the information isreadily available in the I/O status table 1520 maintained by theintelligent display module 214, without there being a need tospecifically request the information.

At step 312, the input status information is processed at theintelligent display module 214. For example, if fuel supply pressure ismeasured by one of the sensors 222, then the measured fuel supplypressure may be compared with upper and lower benchmark values todetermine whether the fuel pressure is at an acceptable level, orwhether it is too high or too low. Finally, at step 314, the results ofthe test are displayed to the operator.

As has been previously noted, in addition to performing diagnostictests, the intelligent display module 214 can also be used to provideother services to an operator. For example, the intelligent displaymodule 214 can be used to allow the operator to view engine codes, toview transmission codes, to view ABS codes, and to view CTIS codes. Inpractice, these services can be implemented simply by allowing acquiringthe respective codes from the respective control system 224-230, anddisplaying the codes to the operator. Additionally, the control systems224-230 may automatically transmit fault information on thecommunication network 232, and the intelligent display module 214 canlisten for such fault information and display the fault information tothe user when it appears on the communication network 232.

The intelligent display module 214 also includes sufficient memory toallow maintenance information to be stored therein to implementmaintenance jacket functionality. The maintenance log may consist of atable comprising a variety of fields, such as registration numbers,chassis serial number, vehicle codes, and dates and descriptions ofmaintenance actions performed. This information may be retrieved andmanipulated utilizing the computer 234 when the vehicle 210 is taken toa maintenance depot. If the computer 234 is provided with an interactiveelectronic technical manual (IETM) for the vehicle 210, this allows theIETM to have access to all of the diagnostic data acquired by theintelligent display module 214 as well as all of the maintenance datastored by the intelligent display module 214. This greatly enhances theability to perform vehicle maintenance and diagnostics on the vehicle210.

Additionally, sufficient memory capacity is preferably provided so thatstatus information from the test interface module 221 as well as thecontrol systems 224-230 can be sampled and stored at frequent, regularintervals in a circular data queue (i.e., with new data eventuallyreplacing old data in the circular queue). This allows the intelligentdisplay module 214 to provide a data logger service so that input dataacquired over a period of time can be viewed to allow an assessment ofdynamic conditions leading to a fault to be evaluated. Additionally, thevehicle is preferably provided with one more sensors that indicatewhether a severe malfunction (e.g., the vehicle being involved in anaccident) has occurred. When inputs from these sensors indicates that asevere malfunction has occurred, data logging is stopped, so that dataleading up to the severe malfunction is stored in a manner similar to aso-called “black box recorder.”

Referring now to FIGS. 26-29, as previously mentioned, the controlsystems 12 and 1412 can be used in connection with a variety ofdifferent types of equipment service vehicles. The same is true of thediagnostic system 212. FIGS. 26-29 show some of the vehicles that canemploy the control systems 12 and 1412 and/or the diagnostic system 212.

Referring first to FIG. 26, FIG. 26 is a schematic view of a firefighting vehicle 310 that utilizes the diagnostic system 212. The firefighting vehicle 310 comprises a water dispensing system 315 includingwater hoses, pumps, control valves, and so on, used to direct water atthe scene of a fire. The fire fighting vehicle 310 may also comprise afoam dispensing system 318 as an alternative fire extinguishing system.The fire fighting vehicle 310 also comprises emergency lighting 324,which may in practice be red and white or red, white and blue flashinglights, as well as an emergency horn 326 and an emergency siren 328used, among other things, for alerting motorists to the presence of thefire fighting vehicle 310 in transit to or at the scene of a fire. Thefire fighting vehicle 310 may also comprise an extendable aerial 331that supports a basket 332 used to vertically carry fire fightingpersonnel to an emergency situation at the scene of a fire. Thediagnostic system 212 may be used to diagnose vehicle malfunctions inthe manner described above in connection with the vehicle 210, as wellas to diagnose malfunctions of the specialized systems described abovefound on fire fighting vehicles. Of course, the features of the firefighting vehicle 310 in FIG. 26 and the fire fighting vehicle 10 ofFIGS. 1-2 (including the features pertaining to the I/O status table1520 described in connection with FIGS. 9-12) may be combined.

Referring now to FIG. 27, a schematic view of another type of equipmentservice vehicle 360 that utilizes the diagnostic system 212 of FIGS.22-25 is shown. The equipment service vehicle 360 is a mixing vehiclesuch as a cement mixing vehicle. The mixing vehicle 360 comprises arotatable mixing drum 362 that is driven by engine power from the engine240 via a power takeoff mechanism 364. The mixing vehicle 360 alsoincludes a dispenser or chute 368 that dispenses the mixed matter ormaterial, for example, mixed cement. The chute 368 is moveable to allowthe mixed cement to be placed at different locations. The chute 368 mayswing from one side of the concrete mixing vehicle 360 to the otherside. Rotation of the mixing drum 362 is controlled under operatorcontrol using an operator control panel 366 including chute and drumcontrols comprising one or more joysticks or input devices. Additionalcontrols may be provided inside the operator compartment for driver orpassenger control of the drum 362 and chute 368, for example, adash-mounted control lever to control drum rotation direction, aconsole-mounted joystick to control external hydraulic valves for chuteup/down and swing right/left. Drum rotation start/stop may be controlledusing a switch on top of the joystick lever. Outside controls mountedmay include chute up/down and swing right/left and remote enginethrottle. Drum rotation direction controls may be mounted on right sideof front fender. The diagnostic system 212 is used to diagnose vehiclemalfunctions in the manner described above in connection with thevehicle 210, as well as to diagnose malfunctions of the specializedsystems described above found on mixing vehicles.

The mixing vehicle 360 may also include the control system 1412described above. In such an arrangement, for example, an interfacemodule 1420 is located near the operator control panel 366 receivingoperator inputs which the control system 1412 uses to control of themixing drum 362. An additional interface module 1420 may also beprovided in an operator compartment of the mixing vehicle 360 tointerface with input devices inside the operator compartment whichpermit driver control of the mixing drum 362. Interface modules 1420 arealso connected to output devices such as a drive mechanism that controlsrotation of the mixing drum 362 and a drive mechanism that controlsmovement of the chute 368. For example, if drum and chute movement aredriven by engine power from the engine 240 via a power takeoff mechanism364, the interface modules 1420 may be used to control output devices1450 in the form of electronically controlled hydraulic valves thatcontrol the flow of hydraulic power from the engine to the mixing drumand electronically controlled hydraulic valves that control the flow ofhydraulic power from the engine to the chute. Alternatively, if electricdrive motors are used to drive drum and chute movement (for example, inthe context of a mixing vehicle implemented using the electric vehicle1910 as described above), then the interface modules 1420 may be used tocontrol the drive motors. In operation, inputs are received from theoperator controls at one interface module 1420 may be transmitted to theinterface modules 1420 that control the valves during I/O statusbroadcasts, which in turn control operation of the drum 362 and chute368 based on the operator inputs. Other devices, such as air dryers, aircompressors, and a large capacity (e.g., 150 gallon) water system may beconnected to interface modules 1420 and controlled in accordance withoperator inputs received from similar input devices at the operatorpanels and transmitted over the communication network. Additionalinterface modules 1420 may be used to receive inputs from input devices1440 in the operator compartment and control output devices 1450 such asFMVSS lighting as described above.

Referring now to FIG. 28, a schematic view of another type of equipmentservice vehicle 370 that utilizes the diagnostic system 212 of FIGS.22-25 is shown. The equipment service vehicle 370 is a refuse handlingvehicle and comprises one or more refuse compartments 372 for storingcollected refuse and other materials such as goods for recycling. Therefuse handling vehicle 370 also includes a hydraulic compactor 374 forcompacting collected refuse. The hydraulic compactor 374 is driven byengine power from the engine 240 via a power takeoff mechanism 376. Therefuse handling vehicle may also include an automatic loading or tippingsystem 378 for loading large refuse containers and for transferring thecontents of the refuse containers into one of the compartments 372. Theloading system 378 as well as the hydraulic compactor may controlledunder operator control using a control panel 379. The diagnostic system212 may be used to diagnose vehicle malfunctions in the manner describedabove in connection with the vehicle 210, as well as to diagnosemalfunctions of the specialized systems described above found on refusehandling vehicles.

The refuse handling vehicle 370 may also include the control system 1412described above. In such an arrangement, an interface module 1420 islocated near the hydraulic compactor 374 and controls valves associatedwith the hydraulic compactor 374. Another interface module 1420 locatedadjacent the automatic loading or tipping system 378 controls hydraulicvalves associated with the system 378. Again, the interface modules 1420may be used to control the drive motors instead of hydraulic valves inthe context of. Another interface module 1420 is located adjacent theoperator control panel 379 and is connected to receive operator inputsfrom input devices 1440 which are part of the control panel 379. Inoperation, inputs are received from the operator controls at oneinterface module 1420 and are transmitted to the interface modules 1420that control the hydraulic valves during I/O status broadcasts, which inturn control operation of the hydraulic compactor 374 and loading system378 based on the operator inputs. Additional interface modules may beused to receive inputs from input devices 1440 in the operatorcompartment and control output devices 1450 such as FMVSS lighting asdescribed above.

Referring now to FIG. 29, a schematic view of another type of equipmentservice vehicle 380 that utilizes the diagnostic system 212 of FIGS.22-25 is shown. The equipment service vehicle 380 is a snow removalvehicle and comprises a snow removal device 382 which may, for example,be a rotary blower, plow, or sweeper. The snow removal device 382 may bedriven by engine power from the engine 240 via a power takeoff mechanism384 to remove snow from a region near the snow removal vehicle 380 asthe snow removal vehicle 380 is moving. The diagnostic system 212 may beused to diagnose vehicle malfunctions in the manner described above inconnection with the vehicle 210, as well as to diagnose malfunctions ofthe specialized systems described above found on snow removal vehicles.

The snow removal vehicle 380 may also include the control system 1412described above. An interface module 1420 located adjacent an operatorcompartment receives operator inputs from input devices 1440 located inthe operator compartment. One or more additional interface modules 1420receive the operator input during I/O status broadcasts, and in responsecontrols various output devices 1450 such as FMVSS lighting as describedabove. Preferably, the snow removal vehicle 380 employs the teachings ofU.S. Pat. No. 6,266,598, entitled “Control System and Method for a SnowRemoval Vehicle,” hereby expressly incorporated by reference. Thepreferred snow removal vehicle disclosed therein comprises an impeller,an engine system, and an engine control system. The engine systemincludes a traction engine which is coupled to drive wheels of the snowremoval vehicle, and is adapted to drive the drive wheels to drivemovement of the snow removal vehicle. The engine system also includes animpeller engine which is coupled to the impeller and is adapted to drivethe impeller to drive snow removal. The engine control system receivesfeedback information pertaining to operation of the impeller, andcontrols the engine system based on the feedback information. The enginecontrol system includes a communication network, a microprocessor-basedtraction engine control unit which is coupled to the traction engine andis adapted to control the traction engine, a microprocessor-basedimpeller engine control unit which is coupled to the impeller engine andis adapted to control the impeller engine, and a microprocessor-basedsystem control unit. The system control unit is coupled to the tractionengine control unit and the impeller engine control unit by way of thenetwork communication link. The system control unit is adapted toreceive the feedback information pertaining to the operation of theimpeller, and to generate a control signal for the traction enginecontrol unit based on the feedback information.

Advantageously, due to the utilization of a network architecture in thepreferred embodiment, the diagnostic system is able to use sensors andother sources of information that are already provided on the vehicle,because it is able to interact with other vehicle control systems suchas the engine control system, the anti-lock brake control system, thecentral tire inflation control system, and so on, via a communicationnetwork. The fact that the diagnostic system is connected to these othersystems, which are all typically capable of providing a vast array ofstatus information, puts this status information at the disposal of thediagnostic system.

Further, due to the utilization of an intelligent display module in thepreferred embodiment, it is possible for the intelligent display moduleto be connected to the communication network and collect information asnecessary for a variety of purposes. Thus, the preferred intelligentdisplay module is microprocessor-based and is capable of executingfirmware to provide additional functionality such as data logging,accident reconstruction, and a vehicle maintenance record. Again, thisfunctionality can be achieved by taking advantage of the informationavailable from the vehicle subsystems by way of the networkarchitecture.

Moreover, by mounting the intelligent display module on board thevehicle in the preferred embodiment, for example, in an operatorcompartment, it is not necessary to bring the vehicle to a maintenancedepot to have vehicle malfunctions diagnosed. The services offered bythe intelligent display module are available wherever and whenever thevehicle is in operation.

Referring now to FIG. 30, an overview of a system 410 that utilizes thediagnostic system 212 is illustrated. The system 410 interconnects thecomputing resources of a plurality of vehicles 411-414 with those of amaintenance center 416, a manufacturer facility 417, and a fleet manager418 using a communication network 420. Of course, although four vehiclesare shown, it is possible to use the system 410 in connection with feweror additional vehicles. Also, although in the preferred embodiment thesystem 410 includes all of the devices shown in FIG. 30, it is alsopossible to construct a system that uses only some of the devices inFIG. 30.

The vehicles 411-414 are assumed to be military vehicles, although thevehicles could also be any of a variety of other types of vehiclesincluding the other types of equipment service vehicles described herein(e.g., fire fighting vehicles, concrete transport and delivery vehicles,military vehicles, ambulances, refuse transport vehicles, liquidtransport vehicles, snow removal vehicles, and so on). The vehicles 411each have a control system 1412 as previously described, and thereforethe on-board computer system 422 includes a plurality of interfacemodules 1420. The vehicles 411-414 each include an on-board computersystem 422 which further includes the test control module 215 and theoperator interface 218 previously described above in connection withFIGS. 22-29. The on-board computer system 422 also includes a web serverprogram 423 and is coupled to a global positioning system (GPS) receiver425. Although these features are discussed in connection with thevehicle 411 in FIG. 30, it should be noted that the vehicles 412-414include these features as well (although the vehicles 411-414 need notall be the same type of vehicle).

The web server program 423, which is executed on the intelligent displaymodule 214 or on another computer connected to the network 232, allowsan operator using the maintenance center computer system 424, themanufacturer computer system 432 and/or the fleet management computersystem 437 to access vehicle information. For example, the operator isgiven access to the information in the I/O status table 1520 maintainedby the intelligent display module 214 using a web interface. Thus, theoperator can click on depictions of individual input devices 40, 1440and output devices 50, 1550, and the web server 423 responds byproviding information as to the status of those devices. Additionally,the operator is also given access to information from the controlsystems 224-230. Thus, the operator can click on a depiction of thecentral tire inflation system 234 to obtain central tire inflationsystem information, can click on a depiction of the brake system 236 toobtain brake system information, can click on a depiction of thetransmission system 238 to obtain transmission system information,and/or can click on a depiction of the engine 240 to obtain engineinformation. When the web server 423 receives these operator inputs, theweb server 423 provides the requested information to the operator by wayof the communication network 420. It may also be desirable to providethe on-board computer system 422 with web-browser functionality to allowthe on-board computer system 422 to obtain information from themaintenance center computer system 424 and/or the manufacturer computersystem 432.

Rather than clicking on various vehicle components, a list of I/O statesfor all or some of the I/O devices 1440 and 1450 and/or I/O statusinformation from the control systems 224-230 may be displayed to theoperator. For example, a particular input or output may be identifiedwith a descriptive identifier (e.g., “PTO Solenoid”) with an indicationas to whether the input/output is on or off (e.g., by placing the words“on” or “off” next to the descriptive identifier, or through the use ofa color indicator whose color varies according to I/O state). For analogI/O devices, meters, gauges, or other image corresponding to the I/Odevice may be displayed, without displaying the entire vehicle andwithout use of the web server 423 and web browsers 430, 435, 438.Various examples are shown in FIGS. 37-47. All of the I/O statusinformation is preferably capable of being transferred automatically andon a real-time basis for real-time remote monitoring of any aspect ofoperation of the vehicle 411.

In an alternative embodiment, the web server 423 may be provided in anoff-board computer system and the on-board computer system 422 can postinformation to the web server 423. The off-board computer system used toimplement the web server may for example be any of the computer systems424, 432, 437 discussed below. This would allow the same functionalityto be achieved while at the same time reducing the amount ofcommunication required between the on-board computer system 422 and theoff-board computer systems that wish to view information from theon-board computer system 422.

The GPS receiver 425 permits vehicle position to be determined. Theon-board computer system 422 can then transmit the vehicle positioninformation to the computer systems 424, 432, 437 along with the otherI/O status information.

The maintenance center 416 is a facility to which the vehicles 411-414may be taken for maintenance. For example, in the context of a fleet ofmilitary vehicles, the maintenance center 416 may be a maintenance depotthat is used to service the military vehicles. For a fleet of municipalvehicles, the maintenance center may be a municipal facility where thevehicles are stored and maintained. Alternatively, the maintenancecenter 416 may be operated by a private outside contractor such as aservice station hired to maintain and service municipal vehicles.Likewise, where the fleet of vehicles is privately owned, themaintenance center 416 may be internally operated or operated by anoutside contractor. The structure and functions of the maintenancecenter computer system 424 may be combined with those of the computersystems 432 or 437, for example, where the maintenance center isowned/operated by the manufacturer 417 or the fleet manager 418.

The computer system 416 of the maintenance center 416 further includes amaintenance scheduling system 427, an inventory management system 428, adiagnostic program 429 and a browser and/or server program 430. Themaintenance scheduling system 427 is a program executed by themaintenance center computer system 424 that develops and maintains aschedule (typically, at specified time slots) for vehicle servicing atthe maintenance center 416. The inventory management system 428 is aprogram that monitors in-stock inventory of replacement parts for themaintenance center 416. A “part” is any device or substance (system,subsystem, component, fluid, and so on) that is part of the vehicle andnot cargo. Typically, each part has an associated part number thatfacilitates ordering and inventory management. The diagnostic program429 may be the same as the diagnostic program 217 previously described.In this regard, it may be noted that the computer system 416 is capableof manipulating the I/O devices of the vehicle 411 by sendingappropriate commands to the control system 1420 of the vehicle 411.

The web browser 430 allows an operator of the maintenance centercomputer system 424 to access the information content of the web siteprovided by the web server 423 of the vehicle 411. Thus, as previouslydescribed, the operator can click on various vehicle subsystems orinput/output devices, and the web server 423 will receive these inputsand provide the operator with the requested information. The Internetbrowsing program may be any one of many different types of software froma full scale browser down to a simple browser that is commonly used forInternet enabled wireless phones, depending on how information ispresented to the operator.

The manufacturer 417 is a manufacturer of the vehicles 411-414 and/or amanufacturer of replacement parts for the vehicles 411-414. Themanufacturer 417 has a manufacturer computer system 432 which includesan inventory management system 433, a diagnostic program 434, and a webbrowser 435. The inventory management system 434 is a program thatmonitors in-stock inventory for the manufacturer 417. The web browser435 and the diagnostic program 434 may be the same as described inconnection with the diagnostic program 429 and the web browser 430 ofthe maintenance center computer system 424.

The fleet manager 418 is the entity that owns or leases the vehicles411-414, for example, a municipality, the military, and so on. The fleetmanager 418 has a fleet manager computer system 437 that includes a webbrowser 438. The web browser 438 allows the fleet manager 418 to monitorthe status and position of the vehicle 411 as previously described inconnection with the web browser 430.

The computer systems 422, 424, 432 and 437 of the vehicles 411-414, themaintenance center 416, the manufacturer 417, and the fleet manager 418,respectively, are all connected to the communication network 420. Thecommunication network 420 is preferably the Internet. The Internet ispreferred because it is a convenient and inexpensive network thatprovides worldwide communication capability between the computer systems422, 424, 432 and 437. Additionally, the Internet permits communicationbetween the on-board computer system 422 and the maintenance centercomputer system 424 using electronic mail format or other commonly usedInternet communication formats. Preferably, security/encryptiontechniques are used which allow the Internet to be used as a secureproprietary wide area network. A variety of other types of networks mayalso be used, such as a wireless local area network, a wireless widearea network, a wireless metropolitan area network, a wireless long-haulnetwork, a secure military network, or a mobile telephone network.

The on-board computer system 422 is preferably connected to the Internetby way of a wireless modem. Preferably, the on-board computer system 422uses a cellular telephone modem with coverage in the geographic regionin which the vehicle 411 operates and capable of establishing a dial-upconnection to the Internet by way of a telephone link to an Internetservice provider. Other communication networks and devices may be used,such as a satellite link, infrared link, RF link, microwave link, eitherthrough the Internet or by way of other secure networks as mentionedabove. Additionally, the on-board computer system 422 may use some otherform of custom or commercially available software to connect to thecomputer systems 424, 432 and 437, especially if an Internet connectionis not used.

Referring now to FIGS. 31-32, the operation of the system 410 to order areplacement part and schedule maintenance for the vehicle 411 isillustrated. FIG. 31 shows the operation of the on-board computer system422. FIG. 32 shows the operation of the maintenance center computersystem 424 which cooperates with the on-board computer system 422.Referring first to FIG. 31, at step 441, a diagnostic test is performedto measure a vehicle parameter. As previously mentioned, the system 411is preferably used in connection with the diagnostic system 212described in connection with FIGS. 22-29, and the diagnostic test may beany of the tests described in connection with FIGS. 22-29 or othertests.

Preferably, step 441 is performed continuously throughout normaloperation of the vehicle 441. Thus, as the vehicle 411 travels on thehighway, for example, vehicle operating conditions are monitored and thetests identified in Table II are performed without operator involvement.

At step 442, the test control module 215 determines that maintenance isrequired, for example, by comparing the measured operating parameters toreference values for the operating parameters. The operating parametersmay, for example, include temperatures, pressures, electric loads,volumetric flow of material, and so on, as described above. Upper and/orlower reference values are stored in a database or table in the testcontrol module 215. The reference values for the operating parametersmay be stored based on values provided by the manufacturer of thevehicle 411 or are set based on information provided by the manufacturerand based on actual usage conditions. In addition, the reference valuesmay be updated periodically when the on-board computer system 422connects to the appropriate maintenance center computer system 424. Ifthe measured operating parameter is outside an acceptable range asdefined by the reference values, then maintenance is required.

At step 443, when it is determined that an operating parameter isoutside an acceptable range at step 442, the diagnostic system 212 faultisolates to a replaceable part. The manner in which step 443 isperformed depends on the parameter that is out of range. Many types ofvehicle parts wear out regularly, and the fact that a particularparameter is out of range often has a high correlation with a particularpart being in need of replacement. For example, and with reference toTable II, if the measured parameter is battery resistance change, andthe battery resistance change is out of range, then this indicates thatthe battery needs to be replaced. If the measured parameter is startercurrent, and the starter current is low, then this indicates that thestarter needs to be replaced. If the measured parameter is currentthrough an output device (e.g., a light bulb), and no current flowsthrough the output device, then this indicates that the output deviceneeds to be replaced. If the measured parameter is a fluid level, andthe fluid level is below a predetermined level as indicated by a fuelgauge, then this indicates that additional fluid is required to replacelost fluid. Additionally, a significant number of routine maintenanceitems may be identified in this manner. Thus, the diagnostic system 212preferably monitors actual usage (e.g., distance traveled, engine hours,and so on) to determine when routine maintenance (e.g., a tire change,an oil change) is required, indicating that one or more parts (e.g., oneor more tires, or the oil and the oil filter) of the vehicle are in needof replacing. (In this regard, it may be noted that the process of FIG.31 may also be used even where no replacement part is ordered, forexample, to schedule a preventive maintenance checkup based on actualvehicle usage.)

Further, the I/O states of the input devices 1440 and output devices1450 may be compared to detect inconsistencies and thereby locatedevices that are in need of replacing. For example, if the input stateof a particular input device 1440 is inconsistent with I/O statusinformation received from one or more other (possibly, redundant)devices, then this indicates that the particular input device 1440 is inneed of replacing. Moreover, the I/O circuitry of the interface modules1420 provides additional health and operation information regarding theI/O devices 1440 and 1450. For example, if the voltage across aparticular input device is zero volts, and the expected input range forthat input device is +1.0 volt to +5.0 volts, then this indicates thatthe input device 1440 is in need of replacement. Alternatively, if agiven output device 1450 never draws any power regardless of theperceived output state of the output device 1450, then this indicatesthat the output device 1450 is in need of replacing. Thus, by testingvoltage and current conditions in the I/O circuitry of the interfacemodules 1420, an indication of particular input devices 1440 or outputdevices 1450 that are in need of replacing may be obtained.

In a limited number of circumstances, it is desirable for the faultisolating step 443 to be performed at least partially in response tooperator inputs. Specifically, operator inputs are desirable when anout-of-range parameter indicates that maintenance is required, but theparameter (or combination of parameters) that is out-of-range is nothighly correlated with failure of a particular part. In this case, thenoperator inputs may be used in combination with other inputs to identifywhich part is in need of replacing. For example, the diagnostic system212 may be able to fault isolate to a limited number of parts or groupsof parts which potentially need to be replaced. The parameters that areout of range, along with other diagnostic data and the parts or groupsof parts that potentially need to be replaced, are then displayed to theoperator using the display 219. The operator may for example be thedriver of the vehicle or maintenance personnel assigned to maintain orrepair the vehicle. Operator inputs are then acquired which make a finalselection of the parts or groups of parts to be replaced based on theoperator's professional judgment or other information.

Additionally, operator input may also be desirable in the case ofreplacement parts that have a cost which exceeds a predeterminedthreshold level (e.g., replacement parts that are considered to beparticularly expensive). In this case, the results of the faultisolating step 443 are preferably displayed to the operator, and theoperator is requested to confirm that the fault isolating step 443 hasbeen performed correctly. In a particularly preferred embodiment, theoperator is further requested to provide an identification code (toidentify the operator and confirm that the operator has the requisiteauthority to make such a determination) and/or an authorization code (toprovide a paper trail and confirm that any required authorizations fororder the replacement part have been received). The on-board computersystem 424 then verifies that the identification code identifies anoperator having the requisite authority to order such a part and requestsuch maintenance, and/or confirms that the authorization code is validand therefore any required authorizations for order the replacement parthave been received.

The health and operation information that is used by the diagnosticsystem 212 to perform step 443 may be derived from a variety of sources.First, as previously noted, the control systems 224-230 have built intest capability and are able to provide health and operation informationregarding the respective controlled subsystems 234-240. Additionally,numerous sensors may be located throughout the vehicle and connected toone of the interface modules 1420. Further, the I/O circuitry of theinterface modules 1420 provides additional health and operationinformation regarding the I/O devices 1440 and 1450 to which it isconnected. To the extent that the amount of health and operationinformation available to the diagnostic system 212 is increased (e.g.,through the use of improved built-in test capabilities or the use ofadditional sensors), the ability of the diagnostic system 212 to faultisolate will be improved.

At step 444, which may be performed concurrently with step 443, thediagnostic system 212 identifies the part number of the replacement partrequired to return the vehicle 411 to operating condition. Thus, if thediagnostic system 212 determines that the battery needs to be replacedat step 443, then at step 444 the diagnostic system identifies the partnumber of the battery to be replaced. Step 444 is preferably performedusing a database that identifies all parts on-board the vehicle 411,including part numbers and pricing information. The data base ispreferably located on the on-board computer system 422 and is integratedwith the previously-discussed maintenance jacket which is stored in thecomputer system 422 and which comprises a log of maintenance activitiesperformed on the vehicle 411. In order for the data base to be keptcurrent, the database is updated periodically by establishing anInternet link with the manufacturer computer system 432. Alternatively,the database may be stored at the fleet manager computer system 437 andaccessed via network connection over the communication link 420. Forexample, this is advantageous if the functionality of the fleet managercomputer system 437 is combined with the functionality of themaintenance center computer system 424 in a single computer system. Inthis situation, the inventory management system 428 can maintaininventory levels in a manner that takes into account how many vehiclesuse a particular part. The inventory management system 428 can alsoquery the diagnostic systems 212 of particular vehicles to assess howsoon particular parts may need to be replaced.

At step 445, after the fault has been isolated and the replacement parthas been identified, a request for a replacement part along with arequest for maintenance is transmitted to the maintenance centercomputer system 424. If the parts data base is stored at the on-boardcomputer system 422, then the request for the replacement part maysimply comprises a request for a part identified by a particular partnumber (e.g., “Battery, part no. 1234”). If the parts data base isstored at the maintenance center computer system 424, then the requestfor the replacement part simply comprises a request for a new partwithout specifying a part number. The operator identification codeand/or authorization code are preferably also transmitted.

Step 445 is preferably performed whenever a part is identified that isin need of replacing. However, step 445 may also be performed in delayedfashion after the maintenance center computer system 424 initiatescontact with the on-board computer system 422 and queries whether anyparts and maintenance are required.

Referring now also to FIG. 32, FIG. 32 shows the operation of themaintenance center computer system 424 after the parts and maintenancerequest is transmitted from the on-board computer system 422. At step451, the maintenance center computer system receives the request for theparts and maintenance request from the on-board computer system 422. Atstep 452, the maintenance center computer system 424 verifies theauthorization for the ordered part. For example, the maintenance centercomputer system 424 confirms that the identification code identifies anoperator having the requisite authority to order such a part and requestsuch maintenance, and/or confirms that the authorization code is validand therefore any required authorizations for order the replacement parthave been received.

At step 453, the maintenance computer system 424 accesses the inventorymanagement system 428 for the maintenance center 416 to determine if therequested part is available in on-site inventory. For example, for lowdollar value or common parts, the part is likely to already be availableon-site. For high dollar value or irregular parts, the part may have tobe ordered from the manufacturer 417.

At step 454, assuming the requested part is determined to be notavailable on-site in step 453, then the maintenance center computersystem 424 places an on-line order for the part with the manufacturercomputer system 432. When the manufacturer computer system 432 receivesthe order, it accesses the inventory management system 433. If the partis on-hand at the manufacturer 417, the part can be shipped to themaintenance center for next day delivery. If the part is not on-hand,the manufacturer computer system 432 determines the amount of time untilthe part will be available (taking into account any backlog of orders).The manufacturer computer system 432 then transmits a message to themaintenance center computer system 424 confirming the order andindicating an expected delivery date for the part to the maintenancecenter. This information may, for example, be sent in the form of e-mailmessage that is received by automatic scheduling program as well as apersonal e-mail account associated with a supervisor or manager of themaintenance center 416.

At step 455, the maintenance center computer system 424 receives themessage from the manufacturer computer system 432 confirming the orderand indicating the expected delivery date. At step 456, the maintenancecenter computer system 424 accesses the maintenance scheduler 427 todetermine the next available maintenance slot after the replacement partis delivered.

At step 457, the maintenance center computer system 424 confirmsavailability of the vehicle 411, for example, by transmitting a messageto the fleet management computer system 437 to confirm vehicleavailability. Alternatively, a message may be sent to the operator ofthe vehicle 411 and displayed using the 219 to prompt the operator toconfirm vehicle availability (shown as step 446 in FIG. 31). As afurther alternative, the vehicle 411 may be programmed with usagescheduling information, so that the vehicle is able to determine whetherit is available during a given time slot. If the vehicle 411 is notavailable during a given time slot, then another time slot isconsidered.

At step 458, the maintenance center computer system 424 transmits anorder and maintenance scheduling confirmation message to the on-boardcomputer system 422. Referring back to FIG. 31, at step 447, the orderand maintenance scheduling confirmation message is then received by theon-board computer system and, at step 448, displayed to the operator ofthe vehicle 411.

In some situations, after connecting, the maintenance center computersystem 424 may completely control diagnosis of the problem, for example,under the control of an operator at the maintenance center 416. Thus,the operator can execute a diagnostic program that directly manipulatesI/O states of the input devices 1440 and output devices 1450, and/orthat interfaces with the control systems 224-230 to control a respectiveone of the systems 234-240. In this regard, it may be noted that, in thepreferred embodiment, all electric/electronic devices that are notdirectly connected to one of the control systems 224-230 are directlyconnected to one of the interface modules 1420. Therefore, a remoteoperator at the maintenance center 416 can have complete control of allelectric devices on board the vehicle 411, and can control such thingsas engine ignition, engine cranking, and so on.

The maintenance center computer system 424 may also download adiagnostic program that is then used by the on-board computer system422. Also, diagnostic data can be transmitted to the maintenance centercomputer system 424 to create a record of the tests performed androutines run for use in diagnosing future problems or for analyzing pastproblems.

Referring now to FIG. 33, in another embodiment, the system 400 is usedto distribute recall information for the vehicle 411 and to schedulemaintenance in connection with the recall. The recall notice informationis transmitted from the maintenance center computer system 424 and, atstep 441′, is received at the on-board computer system 422. At step442′, the on-board computer system 422 confirms the applicability of therecall. For example, the on-board computer system 422 confirms that thevehicle 411 is configured in such a manner that it utilizes the partthat is the subject of the recall. Steps 441′ and 442′ roughlycorrespond to steps 441-444 in FIG. 31, in as much as both groups ofsteps identify a part that is in need of replacing. Thereafter, theoperation of the on-board computer system 422 and the maintenance centercomputer system 424 is generally the same as previously described, withthe two computer systems 422 cooperating to schedule the vehicle 411 formaintenance to replace the part that is the subject of the recall.

In an alternative embodiment, the recall information may be transmitteddirectly from the manufacturer computer system 432 to the on-boardcomputer system 422. For example, if the vehicle 411 is not part of afleet of vehicles, and may be serviced at any one of a plurality ofdifferent repair centers, the recall notice information may be simplydisplayed to the operator of the vehicle 411 using the display 219. Theinformation sent to the operator preferably includes a notice that thevehicle 411 is the subject of a recall, information regarding compliancesuch as nearby service centers available to perform the recallmaintenance, and other information. The operator then has the option ofscheduling maintenance to comply with the recall. However, it isnecessary for an operator input to be received (e.g., a key press)indicating that the recall information has been considered in order toremove the recall information from the display 219. When the operatorinput is received, a message is transmitted back to the manufacturercomputer system 432 confirming that the operator received the recallinformation. This arrangement allows a manufacturer of the vehicle 411to verify that the recall information was received by the operator ofthe vehicle 411, even if the recall information is ultimately ignored.

The system 410 is also useable for firmware upgrades. Firmware may beupdated on a periodic or aperiodic basis any time the on-board computersystem 422 and the maintenance center computer system 424 establishcommunication. For example, the on-board computer system 422 may connectto the maintenance center computer system 424 to order a replacementpart. If a certain period of time has expired since the last firmwareupgrade then at the time the computer systems connect to order the part,the on-board computer system 422 may check for an available firmwareupgrade. Many embodiments for upgrading firmware are within the scope ofthe present equipment service vehicle system. For example, the operatormay initiate the firmware upgrade process or the on-board computersystem 422 may initiate the process independent of any other need toconnect to the maintenance center computer system 424. Also, there maybe situations where the firmware upgrade is sufficiently important thatthe maintenance center computer system 424 connects to the on-boardcomputer system 422 for the express purpose of upgrading the firmware.Once transferred to the on-board computer system 422, the firmware isthen transmitted to and installed by each of the interface modules 1420within the on-board computer system 422. This arrangement may also beused to install firmware for the control systems 224-230.

Referring now also to FIGS. 34-35, a preferred fleet monitoring, realtime mission readiness assessment, and vehicle deployment method isshown. The method shown in FIGS. 34-35 is useable to obtain a real timeassessment of each vehicle in a fleet of vehicles. This is useful, forexample, in the context of a natural disaster or other emergency when itis not known which vehicles are operational, and the locations of thevehicles is not known. Again, by way of example, the method is describedin the context of the system 400 of FIG. 30. FIG. 34 shows the operationof the fleet management 437. FIG. 35 shows the operation of the on-boardcomputer system 422. Although FIGS. 34-35 are discussed in the contextof the vehicle 411, the process of FIGS. 34-35 are preferably performedin connection with all of the vehicles in the fleet.

Referring first to FIG. 34, at step 475, the fleet management computersystem 437 establishes a communication link with the vehicle 411 usingthe communication network 420. In the context of municipal applications,a cellular telephone modem may be used to connect the vehicle to asecure area of the Internet, allowing the fleet management computer 437to communicate with the vehicles 411-414 by way of the Internet. In thecontext of military applications, a secure military network is used toimplement the communication network 420. At step 476, a vehicle statusreport is acquired from the vehicles 411.

Referring now also to FIG. 35, the operation of the on-board computersystem 422 of the vehicle 411 to generate such a status report is shown.At step 485, a communication link is established with the fleetmanagement computer system 437. Step 485 corresponds to step 475 in FIG.34. At steps 486-494, the on-board computer system 422 performs a seriesof tests that assess the operability of various vehicle subsystems. Bytesting each of the individual subsystems, an overall assessment of themission readiness of the vehicle 411-414 is obtained.

Thus, at step 486, the test control module confirms that thetransmission is in neutral and the brakes are locked. Step 486 isperformed so that when the ignition is engaged at step 487, it is knownthat the vehicle will remain stationary. More complete health andoperational testing may be performed when the engine is turned on,however, the vehicle may be completely unattended and therefore vehiclemovement should be avoided for safety reasons. For example, in thecontext of military vehicles, in which vehicles may be renderedinoperable if a storage site or other stockpile of equipment andvehicles is bombed, it is desirable for the vehicle health and operationto be ascertained even though no operator is present. Likewise, in thecontext of municipal applications, in which vehicles may be renderedinoperable in the event of a natural disaster (such as a tornado orhurricane) or a man-made disaster (such as a large scale industrialaccident or a terrorist attack), it is again desirable for the vehiclehealth and operation to be ascertained even though no operator ispresent.

At step 487, as previously noted, the ignition is engaged. The ignitioninput device which receives an input from the operator (in the form ofan ignition key turning) is preferably one of the input devices 1440.Therefore, by manipulating the I/O states in the I/O status table 1520,the vehicle 411 is commanded to behave as though the ignition key isturned even though no operator is in fact present at the vehicle. Theignition key input state can be manipulated remotely in the same manneras any other input state for an input device 1440 connected to aninterface module 1420.

At step 488, the anti-lock brake control system 226 tests the brakes236. The control system 226 performs built-in self tests to ensure theoperability of the control system 226 and of the mechanical componentsof the brake system 236. If no response is received by the on-boardcomputer system 422 from the brake control system 226, then it isassumed that the brake system 226 has been rendered inoperable. At steps489, 490, and 491, respectively, the central tire inflation system, thetransmission system 238, and the engine system 240 are tested ingenerally the same manner that the anti-lock brake system 236 is tested,specifically, through the use of built-in self test capabilities.Additionally, the tests set forth above in Table II may also beperformed. It should be noted that the systems 234-240 need not betested one after the other as shown in FIG. 35 but, in practice, may betested concurrently. Further, in addition to employing the built-in selftest capabilities of the control systems 224-230, it may also desirableto employ additional health and operation information that is attainableby way of any sensors that are connected to the interface modules 1420.Information pertaining to the operational health of the systems 234-240,such as whether respective system 234-240 passed or failed particulartests, is then logged.

In step 492, the interface modules 1420 test individual input devices1440 and output devices 1450. For example, the input devices 1440 can betested by ensuring that redundant input sensors provide the same inputinformation, and by ensuring that the input devices provide inputsignals that are within an expected range. The output devices 1450 maybe tested by using input devices 1440 which are feedback sensors toevaluate the response of the output devices 1450 to signals that areapplied to the output devices 1450. Additionally, I/O drive circuitry ofthe interface modules 1420 may be used to determine the current throughand/or the voltage across the output devices 1450. Alternatively,separate input devices 1440 may be used which are voltage or currentsensors. This information can be used to assess the consumed power byeach output device 1450 and determine whether the consumed power iswithin a predetermined range.

At step 493, the GPS coordinates of the vehicle 411 are acquired usingthe GPS receiver 425. At step 494, other I/O status information isacquired and logged from the I/O status table 1520. Preferably, all ofthe information in the I/O status table 1520 is logged. As a result, theI/O status report contains information regarding such parameters as fuellevel. Additionally, in the context of multi-purpose vehicles,information regarding the configuration of the vehicle 411 may be storedin the I/O status table 1520. Therefore, after a natural disaster, itwill be known whether a particular vehicle is presently configured witha dump truck variant module, a wrecker variant module, or a snow removalvariant module, for example.

At step 495, the information which logged during steps 487-494 iscompiled into the vehicle status report. Of course, step 495 may also beperformed concurrently as each of the steps 486-493 is completed.Preferably, during step 495, a summary conclusion is also generatedbased on the results of the tests performed during steps 487-494. Forexample, the summary conclusion may be “fully operational” if theresults of the tests performed during steps 487-494 determine that allsubsystems are at or near a level of full operability, “operational withlimited damage” if the test results indicate that one or more subsystemshas sustained significant damage but the vehicle is still useful for atleast some intended purposes, “inoperable” if the test results indicatethat one or more subsystems has sustained significant damage and thevehicle is not useful for any intended purpose, and “inconclusive” ifthe tests could not be performed or if the test results provideconflicting information regarding the operability of the vehicle 411. Atstep 496, the vehicle status report is then transmitted from theon-board computer system 422 to the fleet management computer system437.

Referring back to FIG. 34, after the vehicle status report is acquiredby the fleet management computer 437, the fleet management computersystem 437 displays to an operator the vehicle location information atstep 477 and the vehicle health and operation information at step 478.Preferably, steps 477-478 are performed in the following manner.Specifically, the vehicle location, health, and operation information isdisplayed to the operator of the fleet management computer system 437using the web browser 438. For example, in the context of a fleet ofmunicipal vehicles, the web browser 438 displays a city map with iconsrepresenting the vehicles superimposed on the city map at locationscorresponding to the actual position of the vehicles. The icons aredisplayed in a manner which is indicative of the level of health andoperation of the vehicle. For example, a red icon indicates aninoperable vehicle, a yellow icon indicates a semi-operable vehicle, anda green icon represents a vehicle which is substantially fully operable.Alternatively, only two colors may be used (e.g., green and red), withvarying levels of gradations between red and green being used toindicate a percentage level of operability. Further, the displayed iconspreferably vary according to the type of vehicle represented. Forexample, an icon representing a fire truck may be displayed as a smallrepresentation of a fire truck, whereas an icon representing a wreckervehicle may be displayed as a small representation of a wrecker vehicle.In the context of variant vehicles, the variant vehicle may berepresented in different ways depending on the type of variant modulemounted on the vehicle chassis. In this way, the operator is able toview the city map displayed by the web browser 438 and obtain animmediate overall picture of the real time locations of the operablevehicles available for responding to the natural disaster. Likewise, inmilitary applications, a battlefield commander is able to view a map ofthe battlefield and obtain an immediate overall picture of the locationsof the operable military vehicles. Again, different types of militaryvehicles may be represented using different icons. Further, in bothmilitary and municipal contexts, to obtain additional information, theoperator of the fleet management computer system 437 can click on theiconic representation of a particular vehicle to obtain additionalinformation as previously described.

At step 479, the fleet management computer system 437 acquires operatorcommands for vehicle deployment. For example, in military applications,a commander can control troop movements by clicking on particularvehicles and dragging the vehicles on the screen to new locations on thedisplay of the battlefield map. When the operator clicks on a particularvehicle and moves the vehicle to a new location on the battlefield orcity map, the new location of the vehicle on the map is converted to GPScoordinates, and the new GPS coordinates are transmitted at step 480 tothe vehicle as part of a command from the operator to move the vehicleto the new location. In similar fashion, in municipal applications, afire chief or dispatcher can cause fire trucks to be deployed tospecified locations by clicking and dragging the icon to the desiredlocation on the city map. Once the icon is dragged to the new location,a shadow icon is displayed at the new location until the vehicle reachesthe commanded position, allowing the operator of the fleet managementcomputer system 437 to know the actual vehicle position as well as thevehicle's commanded position. When the vehicle reaches its commandedposition, the shadow icon is no longer displayed.

As will be appreciated, various combinations of the above-describedfeatures have already been described by way of example. However, as willbe appreciated, additional combinations are possible. For example,various types of equipment service vehicles have been described,including fire fighting vehicles, mixing vehicles, snow removalvehicles, refuse handling vehicles, wrecker vehicles, and various typesof military vehicles. All of the features described in connection withone of these vehicles may also be used in connection with any of theremaining types of vehicles.

Referring now to FIG. 36, owners of equipment service vehicles oftendevise particular routes or other practices which are designed toenhance safety of the vehicle and the general public while maintainingoverall efficiency. For example, the owner of the vehicle may have acertain route laid out with a pre-determined number of pickups anddeliveries, which the operator of the vehicle can accomplish in areasonable amount of time without driving the vehicle at an excessivespeed or in an otherwise unsafe manner. Given that these routes havebeen laid out, it is often desirable to have a way of ensuring that thedriver conforms to these routes. FIG. 36 is a flowchart showing theoperation of the system 410 to detect non-conformance to a predeterminedroute.

At step 511 the GPS receiver 425 acquires GPS coordinates for thevehicle 411. At step 512, the GPS coordinates are compared withcoordinates of travel path waypoints. Preferably, either the on-boardcomputer system 422 or the fleet management computer system 437 includesa map of the predetermined travel paths (or a series of predeterminedtravel paths for different tasks). The map of the predetermined travelpath is defined by a series of waypoints which in turned are a definedby a GPS coordinates for specific locations along the travel path. Thetravel path waypoints may be spaced at any distance; however, vehiclepath monitoring will be more accurate to the extent the waypoints arecloser together. Waypoint manager software may be used to define travelspaths and download waypoints for the travel paths into the on-boardcomputer system 422 or the fleet management computer system 437.

If the comparing step 512 is performed at the on-board computer system422, then the waypoints are loaded into the on-board computer system422. If the comparing step 512 is performed at the fleet managementcomputer system 437, then the GPS coordinates acquired during step 511are transmitted to the fleet management computer system 437 by way ofthe communication network 420. The advantage of performing thecomparison at the vehicle is that it eliminates the need for constantcommunication between the vehicle and the dispatch station. Theadvantage of having the comparison performed at the dispatch station isthat it ensures that the dispatch station is constantly updated with thevehicle position, making real time remote monitoring possible.

At step 513, the difference between the actual GPS coordinates with thenearest travel waypoint is compared with a pre-determined amount. If thedifference is greater than a pre-determined amount, then this indicatesthat the operator has deviated from the pre-determined travel path. Eachwaypoint is provided with permissible lateral and longitudinal deviationvalues. Alternatively, single value may be used for simplicity. If thedeviation is more than a pre-determined amount, then an alert message issent to the operator of the dispatcher display at step 514.

If the difference is less than a pre-determined amount, then thedistance between stored waypoints is computed (step 515) and theexpected travel distance since the last waypoint is computed (step 516).Then, at step 517, it is determined whether the vehicle is progressingat an acceptable rate. This is used to determine, for example, whetherthe vehicle is on the side of the road. For example, the driver may havestopped the vehicle and, therefore, still on the travel path, but thedriver is not progressing at an acceptable rate. By providing real timeupdates to the dispatcher, the dispatcher can immediately contact thedriver to ascertain the source of the problem. Additionally, thedispatcher can make a determination as to whether another vehicle shouldbe used to complete the driver's route.

If the driver is still on the route and is progressing at an acceptablerate, then everything appears to be in order and the current position,time, and speed are logged at step 518. The process of FIG. 36 isrepeated at regular intervals. Assuming vehicle position monitoring isperformed by the fleet management computer 437, it is possible toconstruct a map showing the positions of the vehicle 411 throughout theday. Thus, as the driver operates the vehicle, the position of thevehicle is logged at different times. Based on vehicle position as afunction of time, a map is constructed showing the vehicle's positionover time. Additionally, it is possible to log all of the I/O statusinformation throughout the day. Thus, a complete picture of vehicleutilization of the course of a day (or other time period) may beobtained. Additionally, vehicle parameters may be monitored in real timeto diagnose equipment malfunctions, click on the vehicle to obtainadditional information. For example, vehicle loading may be ascertainedto determine whether the vehicle 411 has spare capacity.

According to another embodiment, configurator software may be used toconfigure a control system such as control system 1412 for a vehicle.Different options are often made available to purchasers of equipmentservice vehicles and often the different available options includesignificantly different amounts and/or types of hardware and hence I/Odevices. In order to facilitate design and manufacture of such vehiclesin such situations, the configurator software provides a vehicledesigner with the ability to custom-design a control system 1412 for aparticular vehicle. The configurator software may be provided, forexample, on a Microsoft® Windows™ platform and be provided with atypical windows user interface. The user interface may include variousbuttons representing interface modules and possibly also different typesof I/O devices, such as any or all of the I/O devices mentioned herein.In one embodiment, an object-oriented approach is used such that each ofthe icons is embedded with intelligence regarding the particular type ofmodule or device it represents.

In order to program a new control system 1412, the designer opens up anew file and, for example, clicks on an interface module button to dragan interface module into the designer's workspace. The designer thenclicks on the interface module to open a dialog box that lists inputsand outputs. For example, for an interface module that supports fifteeninputs and fifteen outputs, the dialog box lists fifteen inputs andfifteen outputs. The operator is provided with the ability to configurethe various inputs and outputs of the interface module via the dialogbox. Alternatively or in addition, the operator may be provided with theability to click and drag I/O devices into the workspace and establishconnections between the interface modules and the I/O devices.Individual I/O devices may be provided names (e.g., “left frontheadlight”). For each of the inputs and outputs, information regardingprocessing to be performed by the interface module is specified by theoperator and received by the configurator software. For example, forinputs, parameters such as switch debounce times, input filtering, inputscaling, alarm limits, and other parameters may be specified. Foroutputs, parameters such as PWM frequencies, output scaling, limits, andother parameters may be specified. Also, for output devices, a controlalgorithm or logic may be specified. For example, for an analog outputdevice, a control algorithm such as a PID algorithm may be specifiedthat is a function of one or more of the parameters measured by variousones of the input devices. Likewise, for a digital output device, aBoolean equation may be specified that describes the on/off state of theoutput device as a function of the on/off states of one or more inputdevices coupled to the same interface module and/or to one or moreremaining interface modules. The user interface may also restate theBoolean equation to the operator using device names assigned by theoperator to provide a user friendly description. This process isrepeated for all of the interface modules and all of the I/O devicesthat are to be included on the vehicle. The data that is generated usingthis process is stored in a file structure that can be uploaded into theinterface modules located on the vehicle. In one embodiment, the data isstored as part of an Microsoft Access® data base and the Access database is uploaded into the interface modules.

Each interface module is provided with a generic control program that iscustomized by the configuration data generated during the foregoingprocess. Thus, each interface module is provided with informationregarding the types of I/O devices to which it is connected and the I/Oprocessing that is to be performed in connection with those I/O devices.The firmware of the interface module executes against the configurationdata. Notably, there is no need to compile code and load the compiledcode onto the vehicle, because only data (in most cases) is beinguploaded onto the vehicle. This allows vehicle firmware to be genericfor all vehicles and allows the firmware to be updated at any time.After a new revision of firmware is uploaded, the interface module mayuse the new firmware to execute against the old (albeit still valid)configuration data.

Preferably, for unusual I/O devices, provision is preferably made toallow the user to upload specialized code for the I/O device into theinterface module. Thus, for example, the user may be provided with theability to write an executable program for a particular output deviceand then upload the program with the data for that particular outputdevice. The executable code is then executed by the interface moduleduring operation of the control system 1412. This provides greaterflexibility to employ different types of output devices.

This arrangement is advantageous because it facilitates configuration ofvehicle control systems. This arrangement also allows parts of thevehicle configuration to be configured and maintained independently. Forexample, it is possible to upgrade the firmware without affecting thevehicle configuration. Also, it is easier to provide different users oroperators (e.g., designer, field service operator) with different levelsof access.

E. Steering Control System

Referring now to FIGS. 48-50, a vehicle 110 having a steering controlsystem 112 according to another embodiment of the invention isillustrated. Referring first to FIG. 48, FIG. 48 is an overview of thepreferred steering control system 112. The control system 112 includes aplurality of interface modules 114 a-114 e (collectively, “the interfacemodules 114”), front-rear steering actuator(s) 116 a and rear-rearsteering actuator(s) 116 b (collectively, “the rear steering actuators116”), front steering sensor 118, rear steering sensors 120 a-120 b(collectively, “the steering sensors 120”), operator I/O devices 122,other vehicle I/O devices 124, and one or more electronic control units126 (e.g., engine ECU, transmission ECU, and so on). The control system112 is used to control the steering angle of front-rear and rear-rearwheels 128 a and 128 b (collectively, “the rear wheels 128”), e.g.,responsive to the steering angle of the front wheels 130.

In operation, the vehicle operator uses a steering wheel or joystick(not illustrated) that is mechanically coupled to the front wheels 130to control the steering of the front wheels 130. The steering angle ofthe front wheels 130 is measured by a steering sensor 118, whichtransmits this information to the interface module 114 a, which isassumed herein to be the particular one of the interface modules 114operating as the controller for the steering control system 112. Asdescribed below, various modes of operation exist and in at least someof the modes of operation the interface module 114 a uses stored controlprograms to generate a commanded steering angle for the rear wheels 128as a function of the steering angle of the front wheels 130. Theinterface module 114 a provides control signals to the steeringactuators 116 configured to cause the steering actuators 116 to placethe rear wheels 128 at the commanded steering angle. The actual steeringangle of the rear wheels 128 is measured by the steering sensors 120,and the output of the steering sensors 120 is provided as a feedbacksignal to the interface module 114 a. The interface module 114 aimplements a linear feedback control loop (e.g., aproportional-integral-derivative or “PID” control loop) to adjust thecontrol signals provided to the steering actuators 116 to minimize theerror between the commanded steering angle and the actual steeringangles of the rear wheels 128.

In another embodiment, rather than use a mechanical link between thesteering wheel and the front axle, an electronic link is used. Thus, theinterface module 114 a is used to generate steering angles for allwheels 128 and 130, and feedback control is used to minimize errorbetween the actual steering angles of the wheels 128 and 130 and thecommanded steering angles. Although the vehicle 110 is shown to comprisethree axles, the control system 112 may also be used in connection withvehicles having fewer or additional axles.

In the embodiment of FIGS. 48-49, the control system 112 is implementedusing the interface module 114 a as a controller and the interfacemodule 114 a is one of a plurality of interface modules 114 that form anoverall control system for the vehicle 110. The overall control systemfor the vehicle 110 is preferably constructed in accordance with thecontrol architectures described elsewhere herein. Accordingly, as shownmore clearly in FIG. 49, the interface modules 114 are connected to eachother by way of a communication network 132. As previously described,the interface modules 114 are locally disposed with respect to therespective input and output devices to which each interface module iscoupled so as to permit distributed data collection from the pluralityof input devices and distributed power distribution to the plurality ofoutput devices. Of course, each of the interface modules 114 may, inaddition, be coupled to other non-local input devices and outputdevices, e.g., by way of the communication network 132. For example, theinterface module 114 a is connected to the steering sensors 118 and 120by way of the communication network 132. Further, the control system 112can also include input devices and output devices which are notconnected to the interface modules 114.

The control system 112 is preferably configured such that the interfacemodules 114 are preferably identically constructed and programmed.Further, each of the interface modules 114 broadcasts I/O statusinformation on the communication network 132, and each of the interfacemodules 114 uses the I/O status broadcasts to maintain an I/O statustable 1520, as previously described. Based on the I/O status informationstored in the I/O status table 1520 maintained by each respectiveinterface module 114, the respective interface module 114 executespertinent portions of the control programs to control the output devicesto which it is directly connected. This also allows data from thesteering control system 112 to be broadcast to other interface modulesand devices for use by other parts of the overall vehicle controlsystem. Also, data from the steering control system may be stored in thedata logger 1485 to store information logged during a predeterminedamount of time (e.g., thirty seconds) immediately prior to theoccurrence of one or more trigger events (e.g., events indicating thatthe vehicle 110 has been involved in an accident), as previouslydescribed.

The other vehicle I/O devices 124 are I/O devices that are controlled byother ones of the interface modules 114 besides the interface module 114a. The vehicle 110 may be any of the vehicle types described elsewhereherein (e.g., fire truck, military vehicle, concrete placement vehicle,snow blower, and so on), and the other I/O devices may be I/O devicesassociated with those types of vehicles and/or generic I/O devices(e.g., headlights and dashboard switches) commonly found on most typesof vehicles.

It may also be noted that the control system 112 may be implementedwithout necessarily incorporating the control architectures describedelsewhere herein. For example, rather than the interface module 114 a, astand-alone controller may be used. Most/all of the features describedherein (e.g., those described below relating the graphical userinterface, the error reporting system, and other enhancements) may alsobe implemented in a system that uses a stand-alone controller ratherthan an interface module that is networked with other interface modules.

The control system 112 is shown in greater detail in FIG. 49. Aspreviously indicated, the interface module 114 a is connected to theother interface modules 114 and the steering sensors 118 and 120 by wayof the communication network 132. As shown in FIG. 49, the steeringsensors 118 and 120 each comprise an encoder 134 and a translator 136.The encoders 134 may for example be absolute encoders and are coupled toaxles of the vehicle 110 to measure the steering angles of the wheels128, 130. The translators 136 operate to convert the signals from theencoders 134 into J1939-compatible message for transmission on thecommunication network 132. Use of the encoders 134 is advantageousbecause the encoders 134 do not require adjustment but rather allows thesensor to use its current position to correspond to the straight aheadposition of wheels 130, 128. Also, in the event that one of the encoders134 fails, it typically either stops sending messages to the translatoror it sends messages that are of a random count and easily deciphered asan indication that the encoder 134 has failed. The control system 112recognizes that the encoder 134 has failed and displays a message on thegraphical user interface that the details the location of the encoderand the fact that it has failed. Also, in the event of an encoderfailure, the control system 112 may be configured to automaticallychange the steering mode to front mode only.

Also connected to the communication network 132 is the transmission ECU135 (which is one of the ECUs 126 of FIG. 48). The transmission ECU 135provides the interface module 114 a with information regarding the speedof the vehicle 10. In other embodiments, this information may beprovided by the engine or anti-lock brake system.

The steering actuators 116 comprise a plurality of hydraulic cylindersolenoids including a left front-rear cylinder solenoid 138 a, a rightfront-left cylinder solenoid 138 b, a left rear-rear cylinder solenoid138 c, and a right rear-rear cylinder solenoid 138 d. The solenoids 134are connected to the interface module 114 a and to four (left/right,front/rear) cylinders respectively associated with each of the wheels128. Alternatively, one solenoid and one cylinder may be used for eachaxle. In yet another embodiment, one solenoid and one cylinder isprovided for each wheel and no tie rod is used, allowing the steeringangle of each wheel to be independently controlled. The solenoids 134may for example receive a PWM signal from the interface module 114 a tocontrol hydraulic pressure applied to the four and in turn control thesteering angle of the wheels 128. In one embodiment, a temperaturesensor is used to measure the temperature of the hydraulic fluid, andthe PWM signals applied to the solenoids 134 are compensated to provideconsistent operation of the hydraulic cylinders over a range oftemperatures/oil viscosities.

FIG. 49 also depicts lock actuators 140 a and 140 b and lock sensors 142a and 142 b which are not specifically depicted in FIG. 48. The lockactuators 140 a and 140 b are used to insert or remove a locking pinthat locks the front/rear rear axles. As described below, in certainmodes of operation, the rear wheels 128 are not steered and the rearaxles are locked in the straight-ahead position. In one embodiment, ifone cylinder per axle is used, the lock actuators 140 (and correspondinglocking pins), the encoders 134, and the cylinders 138 may be located onone side of the vehicle to reduce mechanical slippage between thesedevices. The lock sensors 142 a and 142 b provide feedback to confirmthat the rear axles are locked. In one embodiment, the sensors 142 a and142 b comprise limit switches. In another embodiment, the sensors 142 aand 142 b comprise proximity switches that sense proximity of thelocking pin. An advantage of using proximity switches for feedback isthat proximity switches detect the actual position of the locking pin.As a result, if the vehicle 110 is out of calibration (the encoder doesnot accurately indicate the straight ahead wheel position), then thelocking pins will not seat properly and this will be detected by theproximity sensors. Alternatively, a new centered (or “straight ahead”)encoder value could be determined by cycling the system until thelocking pin seats properly and then using the encoder value at which thelocking pin seats as the new centered value. In addition to or insteadof proximity sensors, air pressure switches that change state when airpressure is applied to the locking mechanism may also be used (e.g., fordiagnostics).

The interface module 114 a confirms that the rear wheels 128 arecentered before engaging the lock actuators 140 a and 140 b. Also shownin FIG. 49 is a hydraulic pressure transducer 144, which providesfeedback to the interface module 114 a regarding pressure in thehydraulic system used for steering.

Finally, FIG. 49 also depicts the operator I/O devices 122 of FIG. 48 ingreater detail. The operator I/O devices include a graphical userinterface (GUI) display 146. The display 146 is connected to thecommunication network 132 and may, for example, be located in a drivercompartment of the vehicle 110 such as by being mounted on thedashboard. The display 146 may be a liquid crystal display, a VGA orSVGA display, a heads up display system, or other display system. Thedisplay 146 preferably comprises one or more operator input devices toreceive operator inputs, such as a plurality of keys/pushbuttons, touchscreen system, voice recognition system, and so on. In one embodiment, adisplay with five keys/pushbuttons for operator input is used. Theoperator input devices are used to scroll through menu options or screendisplays, set values, and so on. In another embodiment, the display 146may provide the operator with the ability to view or manipulate I/Ostatus information from other interface modules 114 and electroniccontrol units 126 in addition to the interface module 114 a associatedwith the steering control system 112.

Other operator input devices 147 and output devices 148 may also beprovided. The other input devices 147 may comprise, for example, acalibration/learn switch to set a calibration value, a crab alarmswitch, a key switch to activate the control system 112, a fool-operatedmode switch, and so on. The output devices 148 may comprise, forexample, other actuators (e.g., automatic tire chain actuators), lights,indicators, alarms, and so on.

The interface module 114 a may also send and receive other messages onthe communication network 132. For example, an interface module 115 isshown to be connected to other vehicle I/O devices 124. The interfacemodule 115 may be similar to the translators 136 in that itsfunctionality is limited to receiving/transmitting J1939-compatiblemessages on the communication network 132. Thus, the interface module115 may be connected to mode selector switches, and transmit the inputstatus information for the mode selector switches to the interfacemodule 114 a. The interface module 114 a then operates as though themode selector switches are connected to the interface module 114 a viadedicated, hardwired communication links. For output devices, theinterface module 114 a may determine the desired output state for anyoutput devices connected to the interface module 115 and transmit thisinformation to the interface module 115.

In another embodiment, in addition to the display 146 and other operatorI/O devices 147, 148, the interface module 114 a is provided with awireless (e.g., Bluetooth) interface that allows the interface module114 a to send and receive data from a wireless handheld computer, suchas a personal digital assistant (“PDA”). The PDA provides functionalitythat is redundant to the display 146 and other operator I/O devices 147,148, but provides this functionality in a manner that allows theoperator to interact with the control system 112 from outside thevehicle, e.g., while performing calibration or diagnostic procedures.Preferably, the PDA is able to manipulate and examine all operator I/Odevices on the vehicle 110 associated with other ones of the interfacemodules 114, for example, to allow the operator to start the vehicleusing the PDA. Rather than using a PDA, a removable switch panel withcable link to the vehicle may also be used.

In yet another embodiment, remote steering capability may be provided.For example, for a fire fighting vehicle, a wireless joystick and GUIdisplay may be provided that allows an operator to control movement ofthe vehicle 110 from an aerial basket of the fire fighting vehicle(particularly if the vehicle is provided with outriggers comprising hardrollers instead of pads). Again, the wireless capability may be achievedby providing the interface module 114 a and the wireless operator devicewith corresponding wireless communication interfaces (e.g., Bluetoothcommunicators). As another example, in the context of a traileredvehicle, the ability to steer the vehicle remotely from the front cabcompartment provides an operator with the ability to control steeringfrom a trailer portion of the vehicle, e.g., to control steering of therear wheels only. Such features may be implemented for example by havingthe control system 112 control steering for all wheels directlyresponsive to operator inputs (as opposed to having the operatormechanically control steering of the front wheels using a steering wheeland having the control system 112 control steering of the rear wheelsresponsive to the steering of the front wheels).

Referring to FIG. 50, the control system 112 has several modes ofoperation including a front mode of operation, a coordinated mode ofoperation, and a crab mode of operation. The mode may be controlled bythe interface module 114 responsive to the mode switch positionsselected by the operator. The mode switches can be moved at any time;however, the mode changes will not become effective until the front axlecrosses through center (straight-ahead). Thus, the new mode must firstbe selected and then the front axle must be steered through its centerposition for the new mode to become effective.

In the front mode of operation, the operator steers the front wheels 130using a steering wheel or joystick. The lock actuators 140 engage andthe rear wheels 128 are locked in the straight-ahead position, and onlythe front wheels 130 steer when the steering wheel is turned.

In the coordinated mode of operation, the interface module 114 acontrols the rear wheels 128 so as to turn in the opposite direction ofthe front wheels 130. A desired rear wheel steering angle may be storedin the interface module 114 a as a function of the front wheel steeringangle, such that for any given measured front wheel steering angle adesired rear wheel steering angle may be determined. The relationshipbetween the rear wheel steering angle and the front wheel steering anglemay also be stored in a look-up table or embodied in an equation as afunction of speed. Other information may also be taken into account,such as information from one of the other ECUs 126 or one of the otherinterface modules 114. For example, if one of the ECUs 126 is ananti-lock brake system ECU, traction information may be used to limit orprevent sharp steering maneuvers when traction conditions are low.Information from accelerometers may also be used instead of interfacingwith the anti-lock brake system ECU. Likewise, vehicle loadinginformation may be used to similarly limit or prevent sharp steeringmaneuvers when the center of gravity of the vehicle 110 is believed tobe higher than normal (e.g., because a fluid tank carried by the vehicle110 is full).

Preferably, a deadband exists in the steering relationship, such thatthe interface module 114 a does not turn the rear wheels 128 until afterthe front wheels are steered at least ±5° and preferably ±7° from acalibrated center, depending on speed (see FIG. 51A). The deadband isthen the number of degrees the operator must turn the front wheels 130,right or left, before the rear wheels 128 also turn. As shown in FIG.51A, the deadband and speed relationship from 0-10 mph are programmed tominimize the amount of rear-end-swing when making a sharp 90 degreeturn. From 0-2 mph, the deadband is at its maximum and the rear axlewill not steer. From 2-10 mph, the deadband decreases to ±7°. From 10-20mph the deadband is fixed at ±7°. Once vehicle speed reaches 20 mph, thedeadband progressively increases as the speed increases to reduce thepossibility of making too sharp a turn. When speeds over thirty-eightmph are reached, the control system 112 reverts to front mode andengages the lock actuators 140 once the front wheels 130 reachcalibrated center. In an alternative embodiment, position of the rearwheels 128 is used to determine when to revert to front mode. Thecontrol system 112 returns to coordinated mode when the vehicle 110slows to speed below thirty-eight mph. The control system 112 steers therear wheels 128 in coordinated mode after the axles locks are disengagedand the front axle reaches a value of at least ±7° difference fromcalibrated center, depending on speed. The steering angle of the rearwheels 128 is then proportional (or otherwise related) to the number ofdegrees that the operator steers the front wheels 130 beyond theprogrammed deadband for any given speed.

In the crab mode of operation, the interface module 114 a steers therear wheels 128 with a turn ratio of 1:1 with the front wheels 130. Therear wheels 128 turn in the same direction as the front wheels 130. Whenfront axle crosses calibrated center and the crab mode of operation isselected, the control system 112 changes the steering configuration intocrab mode. The rear cramp angles for the crab mode are capable of anglesas high as 20°. The deadband graph that the interface module 114 afollows for the crab mode is shown in FIG. 51B with a deadband of ⅓° oneither side of calibrated center. Preferably, an audible alarm soundswhen this mode is selected. When a speed greater than 6 mph is achievedand the front axle crosses calibrated center the interface module 114 aswitches to front mode, centers the rear wheels 128 and engages the lockactuators 140 to lock the rear wheels 128 in the straight aheadposition. When a speed less than 5 mph is achieved and the front axlecrosses calibrated center the interface module 114 a returns to crabmode.

As previously noted, in one embodiment, one solenoid and one cylinderare provided for each wheel and no tie rod is used, allowing thesteering angle of each wheel to be independently controlled. If thisconfiguration is employed, smooth crab operation can be obtained byeliminating the Ackerman steer angles in the crab mode of operation.

Other modes of operation may also be employed. For example, additionalcoordinated or crab modes of operation may be employed that providedifferent steering characteristics for specialized modes of operation.This may be useful in situations where the vehicle 110 is of aparticular type (e.g., fire fighting vehicle, military vehicle, concreteplacement vehicle, and so on) and the specialized modes of operation aidthe operator in performing various specialized maneuvering tasks thatthe particular type of vehicle is likely to encounter.

Referring now to FIGS. 52-54, a graphical user interface useable inconnection with the control system 112 will be described in greaterdetail. FIGS. 52-54 are a series of screen shots that may be provided toan operator using the display 146 during operation of the control system112. FIG. 52 is an axle status screen 150 that may be displayed afterthe control system 112 is first powered up and may be the “default”screen during normal operation of the control system 112. The screen 150displays a chassis outline 152 or other representation of the vehicle110 with the front of the chassis being located towards the top of thescreen. The wheels of the chassis outline 152 turn in accordance withthe wheels 128, 130 of the vehicle 110. Fewer or additional wheels maybe displayed if the vehicle 110 has a different number of wheels thanshown in FIG. 48. The screen 150 also includes axle lock status windows153 which display the state of the lock actuators 140 a and 140 b. Whenthe lock actuators 140 a are disengaged, the windows read “UNLOCKED”;when the lock actuators are engaged the windows read “LOCKED.” The upperwindow is the lock status for the lock actuator 140 a and the lowerwindow is the lock status for the lock actuator 140 b. The informationin the windows 153 may be displayed based upon the control signalprovided to the lock actuators 140 a and 140 b, or preferably, based onthe information received from the lock sensors 142 a and 142 b.

The screen 150 also includes a requested mode window 154 which displaysthe steering mode that the operator has selected. In FIG. 52, thecoordinated mode is shown as being selected. The screen 150 alsoincludes a current mode window 155 which displays the steering mode inwhich the control system 112 is actually operating. For example, aspreviously indicated, in an overspeed condition (when the vehicle istraveling at speeds above a predetermined level, such as 38 mph), thecontrol system 112 operates in the front mode even though another modemay be selected. The screen 150 also includes a previous mode window 156which displays the steering mode that the control system 112 will returnto when the vehicle 110 slows down from an overspeed condition. Thescreen 150 also includes a message box 157 which displays specialmessages to the operator such as what conditions must be satisfied tochange a requested mode to a current mode (e.g., “waiting for front tocross center”), error code details, and calibration instructions. Thescreen 150 also includes an error code window 158 which displays anerror code number in the event of an error condition. Table III is anexample of a list of error codes that may be displayed to the operator.

TABLE III Error Code Chart ERROR CODE PROBABLE CAUSE OF CODE 0 No errorscurrently on system (clear screen) 10 Bad CRC from EPROM 11 Firegroundalarm feedback missing 12 No mode switches selected 13 More than onemode switch selected 14 # Axles and translators mismatched 15 Wheel baseis not within range 16 Truck ID invalid 17 Encoder 1 out of range 18Encoder 2 out of range 19 Encoder 3 out of range 20 Axle 2 moved toomuch with pwm ON 21 Axle 3 moved too much with pwm ON 22 Axle 2 movedtoo much with pwm OFF 23 Axle 3 moved too much with pwm OFF 24 Axle 2encoder spike counter exceeded 25 Axle 3 encoder spike counter exceeded31 Speed message not received 32 Display message not received 33 I/Omodule message not received 34 Axle 2 lock stuck 35 Axle 3 lock stuck 36Both locks stuck 41 Axle 1 translator message not received 42 Axle 2translator message not received 43 Axle 3 translator message notreceived 44 Encoder did not move during axle 2 right output 45 Encoderdid not move during axle 2 left output 46 Encoder did not move duringaxle 3 right output 47 Encoder did not move during axle 3 left output 48Axle 1 encoder disconnected 49 Axle 2 encoder disconnected 50 Axle 3encoder disconnected 51 Axle 3 right exceeded 80% range 52 Axle 3 leftexceeded 80% range 53 Axle 2 right exceeded 80% range 54 Axle 2 leftexceeded 80% range 61 Error in calculating turn direction 62 Error inmode selection 63 Divide by zero in Coord mode 64 Hydraulic filter isclogged 65 Battery voltage is low 71 OUTPUT 1-Axle 2 left short toground 72 OUTPUT 1-Axle 2 left short to battery 73 OUTPUT 1-Axle 2 leftopen load 75 OUTPUT 2-Axle 2 right short to ground 76 OUTPUT 2-Axle 2right short to battery 77 OUTPUT 2-Axle 2 right open load 79 OUTPUT3-Axle 3 left short to ground 80 OUTPUT 3-Axle 3 left short to battery81 OUTPUT 3-Axle 3 left open load 83 OUTPUT 4-Axle 3 right short toground 84 OUTPUT 4-Axle 3 right short to battery 85 OUTPUT 4-Axle 3right open load 87 OUTPUT 5-Lock valve short to ground 88 OUTPUT 5-Lockvalve short to battery 89 OUTPUT 5-Lock valve has open load 127 OUTPUT15-Tire chain short to ground 128 OUTPUT 15-Tire chain short to battery129 OUTPUT 15-Tire chain has open load 135 OUTPUT 17-Alarm power shortto ground 136 OUTPUT 17-Alarm power short to battery 137 OUTPUT 17-Alarmpower has open load

The probable cause of the error code may, for example, be displayed inthe message box 157. Preferably, the display 146 provides the operatorwith the error code and accompanying user-friendly message as soon as anerror condition is detected.

Preferably, the control system 112 a has built in diagnostic error codememory and recall functions which allow error codes provided to theoperator to be stored in non-volatile memory. The display 146 preferablystores the last twenty error codes that have been registered. The errorcodes preferably remain in memory even if the vehicle power isdisconnected for an extended period of time or the controller is removedfrom the vehicle.

It may be noted that the error codes in Table III may be generatedthrough the use of intelligent devices and additional sensors. Forexample, the use of translators 136 which provide J1939 messaging ratherthan a hardwired sensor (e.g., potentiometer) facilitates identifyingthe source of a problem. It is possible to determine that a translatorhas become disconnected because it fails to provide J1939 messages, asopposed to a failing encoder which may produce a different result.Additionally, sensors such as the lock sensors 142 and the hydraulicpressure transducer 144 also facilitate diagnostics. Further, comparisonof sensed values for consistency with each other and with expectedvalues may be used to generate the error codes. For example, thesteering angles provided by the steering sensors 118 and 120 may becompared with each other and with what is expected (e.g., based on PWMsignals provided to the steering actuators 116, based on mechanicalconstruction of the vehicle 110, and so on) to check for consistencywith expected values. Also, the steering sensors 118 may be used tocheck for an off-tracking condition. Early diagnosis allows faultydevices to be repaired or replaced in a timely fashion.

As previously indicated, in the preferred embodiment, the display 146includes a plurality of operator input devices. As shown in FIG. 52, thedisplay 146 includes five pushbuttons 159-163. An enter/exit pushbutton159 is used for entering and exiting the screen adjusting mode, and mayfor example be a different color than the other pushbuttons 160-163. Afirst screen adjusting pushbutton 160 is used to move forward to aninput/output screen 165 (see FIG. 53), and is also used to increasecontrast in the screen-adjusting mode. A second screen adjustingpushbutton 161 is used to move back to the input/output screen 165 orthe axle status screen 150, and is also used for decreasing contrast inthe screen-adjusting mode. A third screen adjusting pushbutton 162 isused to update the display data. The pushbutton 162 is only useable toupdate data when viewing the axle status screen 152. The pushbutton 162can also be used to increase the screen back lighting in thescreen-adjusting mode. A fourth screen adjusting pushbutton 163 is usedto decrease the screen backlighting in the screen-adjusting mode.

Referring now to FIG. 53, FIG. 53 is an input/output screen 165 whichshows the state of the input and output circuits from the interfacemodule 114 a and the interface module 115 (connected to the modeselector switches). The screen 165 is useful for troubleshooting and isnot typically used during normal operation of the control system 112.The input/output screen 165 may be accessed using one of the pushbuttons158-163.

The screen 165 comprises an interface module input section 166, aninterface module output section 167, an I/O switch section 168, asteering valve threshold section 169. The input section 166 displayshydraulic filter input information 170 from a differential pressureswitch (transducer 144) on a high-pressure filter. The hydraulic filterinput is on when the hydraulic filter is clean and oil is flowing freelyand is off when the filter is plugged and oil flow is restricted, orthere is a break in continuity between the filter and the interfacemodule 114 a. The input section 166 also displays calibrate switch inputinformation 171 from a calibrate switch input. The input normally reads“OFF” but changes to “ON” when the calibration switch is actuated. Theinput section 166 also displays alarm feedback input information 172.This input reads “OFF” when the crab alarm is off and reads “ON” whenthe crab alarm is sounding. The input section 166 also displays lockfeedback information 173 and 174. The lock feedback information 173reads “OFF” when the lock actuator 140 a on the forward rear axle of atandem rear axle truck is disengaged and reads “ON” when the lockactuator 140 a is engaged. The lock feedback information 174 reads “OFF”when the lock actuator 140 b on the rear most axle of a tandem rear axletruck is disengaged and reads “ON” when the lock actuator 140 b isengaged. Preferably, the state of the lock actuators 140 a and 140 b isprovided by the lock feedback sensors 142 a and 142 b.

The interface module output section 167 displays information 175regarding steering hydraulic valves associated with the solenoids 138a-138 d as well as information 176 regarding other outputs. The foursteering valve outputs displays zero when the valve is off or notsteering, and displays a non-zero number when the valve is steering. Thelow number varies depending on the learned threshold for that valve butmay for example be in a range between 350 and 550. The number increasesas the hydraulic effort required to make a turn increases. The numberdisplayed at each valve changes rapidly and is used primarily as anindicator that the valve is on. When a number is displayed, this meansvoltage is being sent to the valve. The solenoid coil is energized,shifting the spool in the valve, causing the rear axle to turn. Whenmaking a right turn in coordinated mode, the left steering valves turnon so that the rear wheels 128 turn in the opposite direction of thefront wheels 130 to reduce the turning radius. The axle 2 left valve isfor the left valve on the forward rear axle (corresponding to thesolenoid 138 b). The axle 2 right valve is for the right valve on theforward rear axle (corresponding to the solenoid 138 a). The axle 3 leftvalve is for the left valve on the rear most axle of the vehicle 110(corresponding to the solenoid 138 d). The axle 3 right valve is for theright valve on the rear most axle of the vehicle 110 (corresponding tothe solenoid 138 c).

The information 176 includes information regarding an axle lock poweroutput, a tire chain power output (for an automatic tire chainactuator), and an alarm power output. The axle lock power output is anoutput to the electric over air lock valve(s). This output reads “ON”when the locks are unlocked and “OFF” when they are locked. The tirechain power output is an output that engages automatic tire chains. Thisoutput is “ON” when the tire chains are engaged and “OFF” when the tirechains are disengaged. The alarm power output is an output to the crabalarm. This output is “ON” when the crab alarm is on and is “OFF” whenthe crab alarm is off.

The I/O switch section 168 displays information 177 and 178 regardingthe states of various operator input devices. For example, as previouslyindicated, mode selector switches and other switches may be connected tothe interface module 115, and the I/O switch section 168 may be used todisplay information from the interface module 115. Such information maytherefore include information 177 from a foot operated mode switch, acoordinated mode switch, a front switch, a crab switch, and/or possiblyother mode selection switches that select specialized modes of operationpertinent to a particular type (e.g., “COORD_FG” in FIG. 53). Suchinformation may also include information 178 from a tire chains switch.

The steering valve threshold section 169 displays information 179regarding valve thresholds. Valve threshold numbers are set up duringthe calibration and learn cycle. These numbers represent the minimumelectrical signal required to turn the rear axle. These numbers varyfrom left to right and axle to axle but usually are between 350 and 550for a tandem aerial ladder fire truck. These numbers do not changeduring normal operation. If the system is recalibrated or relearned itis likely these numbers will be different after these cycles have beencompleted. If these numbers do not change after the Calibration or LearnCycle, access the axle center screen and press the white pushbuttonbelow the box labeled “DATA” and scroll back to the I/O screen. The axle2 left threshold represents the threshold number of the left valve forthe forward rear axle of a tandem or a single rear axle truck. The axle2 right threshold represents the threshold number of the right valve forthe forward rear axle of a tandem or a single rear axle truck. The axle3 left threshold represents the threshold number of the left valve forthe rear most axle of a tandem axle truck. The axle 3 right thresholdrepresents the threshold number of the right valve for the rear mostaxle of a tandem axle truck. In FIG. 53, the steering valve thresholdsection 169 also displays other miscellaneous information, includingsoftware revision information, such as for control system software,display system software, and so on.

Referring now to FIG. 54, an encoder value screen 180 is shown. Theencoder value screen 180 shows the calibrated center positions, fullcramp positions, real time encoder values, and calibrated deadbandvalues of each axle. The screen 180 is useful for troubleshooting anddoes not need to be used during normal operation of the control system112.

The screen 180 displays information regarding encoder values for thefront axle. This information includes #1 left turn stop information 181which represents the calibrated left turn full cramp encoder value. Theactual left turn encoder value could be greater than this value. Thisinformation also includes #2 left turn deadband information 182 whichrepresents the left turn deadband. When the encoder position number isgreater than this value the rear axles will begin to turn. Thisinformation also includes the #3 front axle calibrated centerinformation which represents the encoders calibrated center position.This information also includes #4 right turn deadband information 184which represents the right turn deadband. When the encoder positionnumber is less than this value, the rear axles begin to turn. Thisinformation also includes #5 right turn stop information 185 whichrepresents the calibrated right turn full cramp encoder value. Theactual right turn encoder value could be greater than this value. Thisinformation also includes front axle encoder position information 192 awhich represents the actual encoder position. This number willcontinually change as the steering wheel is turned.

The screen 180 displays information regarding encoder values for theforward-rear axle or axle #2. Axle 2 is the forward rear axle on atandem rear axle truck. In coordinated mode, a left turn of the rearwheels is when the front of the tires turn left. The left valve turns onwhen making a right turn in coordinated mode. The information displayedby the screen 180 includes #6 left turn cramp angle information 186which represents the left turn full cramp encoder value. Thisinformation also includes #7 axle 2 calibrated center information 187which represents the encoders calibrated center position value. Thisinformation also includes #8 right turn cramp angle information whichrepresents the right turn full cramp encoder value. This informationalso includes axle 2 encoder position information 192 b which representsthe actual encoder position. This number will continually change as therear axle moves.

The screen 180 displays information regarding encoder values for therear-rear axle or axle #3. Axle 3 is the rear most axle on a tandem rearaxle truck. In the coordinated mode, a left turn of the rear wheels iswhen the front of the tires turn left. The left valve turns on whenmaking a right turn in coordinated mode. The information displayed bythe screen 180 includes #9 left turn cramp angle information 189 whichrepresents the left turn full cramp encoder value. This information alsoincludes #10 axle 3 calibrated center information 190 which representsthe encoders calibrated center position value. This information alsoincludes #11 right turn cramp angle information 191 which represents theright turn full cramp encoder value. This information also includes axle3 encoder position information 192 c which represents the actual encoderposition. This number will continually change as the rear axle moves.

The control system 112 can be calibrated to determine the straight-aheadand right and left stop positions for the front wheels 130 and rearwheels 128. The straight-ahead positions are typically used duringsteering to coordinate steering of the front wheels 130 and rear wheels128. Before beginning the calibration procedure it is often desirable toalign the front and rear wheels 130 and 128. This can be done usingconventional aligning techniques and apparatus. Although desirable it isnot necessary to align the vehicle 110 before calibrating the controlsystem 112. Also, it is generally desirable, but not necessary, toperform the calibration procedure with vehicle 110 loaded to its normaloperating weight. For example, if vehicle 110 is a cement truck then itshould be loaded with the normal amount of cement/aggregate before it iscalibrated.

In one embodiment, vehicle 110 may be calibrated as shown in FIG. 55. Atstep 195, the front wheels 130 are positioned to be straight-ahead. Inconnection with step 195, it is generally desirable to place the frontwheels 130 on a turntable or drive the vehicle 110 forward to unwind thetires. Alternatively, if vehicle 110 includes outriggers, vehicle 110may be raised to allow the tires to be easily moved without windingthem, or, alternatively, the tires may be moved while on the ground,raised to allow them to unwind, and then placed back down on the ground.In addition to graphical user interface 146, a handheld device (e.g.PDA, laptop, etc.) that is either wireless or cabled may be used toperform tasks such as ramp engine speed to provide increased hydraulicpower to the outriggers. If a handheld device is used, the operator hasthe advantage of being outside the vehicle 110 to observe what is goingon. Front wheels 130 can be placed in the straight-ahead position byplacing a straight edge across the sidewall of one of the front tires.The straight edge should be in line with the vehicle frame. The distancefrom the frame to the straight edge may be measured at both the frontand rear of the tire. If the two measurements are not the same, thevehicle's steering wheel may be adjusted to equal out the front and rearmeasurements.

Other methods may also be used to position the front wheels 130straight-ahead. For example, commercially available aligning equipment(e.g. equipment available from Hunter Engineering Company, 11250 HunterDrive, Bridgeton, Mo. 63044 or from Bee Line Company, P.O. Box 130, 270062nd St. Court, Bettendorf, Iowa 52722, or others) may be attached tothe front wheels 130 and the steering wheel adjusted until the frontwheels 130 are positioned straight-ahead. In a desirable embodiment,control system 112 is configured to interface with the aligningequipment. The aligning equipment may use a laser tracking system,digital camera system, or any other suitable system to align the frontwheels 130. Control system 112 can read the output of the aligningequipment and automatically determine the straight ahead position of thefront wheels 130. The information (the extent to which the front wheelsare not facing straight ahead) could be fed into the control system 112and displayed on the display. The display indicates to the operator whatneeds to be done to put the wheels in alignment. The control system 112can essentially replace the computer or interface with the computer oncommercial alignment systems. In addition to simply determining whetherthe wheels are positioned straight ahead, the control system 112 may beconfigured to interface with the aligning equipment to assist theoperator of vehicle 110 in aligning the front or rear wheels 130, 128.For example, before calibrating the control system 112, the operator mayconnect the aligning equipment to the vehicle 110 and use the controlsystem 112 to determine whether the wheels are aligned. Control system112 displays any required adjustments (e.g. amount of toe in needed ornumber of turns of the tie rod necessary to achieve the properalignment) to the operator. In a further embodiment, control system 112is able to automatically align wheels 130, 128. For example, the tie rodmay be hydraulically actuated and controlled by control system 112 sothat it can be automatically adjusted when control system 112 determineswheels 130, 128 are out of alignment. In this manner, the operator maysimply and easily align the wheels before starting the calibrationprocedure.

In another embodiment, the straight ahead position of front wheels 130may be determined using a permanent mounted laser and target. Theoperator adjusts the wheels until the laser hit the target, at whichpoint the operator can determine that the front wheels were positionedstraight ahead. Of course, control system 112 may be used to move thelaser until it hits the target. In this case, the control system 112 isable to read the input provided from the target to determine whether thelaser is in the correct position. This configuration does not requirethe driver to leave the cab. In one embodiment, the target may belocated in the wheel well and the laser located on or near the wheelhub.

After positioning the front wheels 130 straight ahead, control system112 recognizes the position of encoder 134 as the straight-aheadposition for the front wheels 130. This is typically done responsive tothe operator pushing a button on the graphical user interface 146 tosignify that the front wheels 130 are in the straight-ahead position. Inan alternative embodiment, other ways may be used to notify the controlsystem 112 that the front wheels 130 are in a straight-ahead position.For example, control system 112 may interface with aligning equipment todetermine the straight-ahead position of the front wheels 130. In thiscase, control system 112 is able to automatically detect when the frontwheels 130 are positioned straight-ahead using the data provided by thealigning equipment.

At step 196, the rear wheels 128 may be placed in a straight-aheadposition in a manner similar to that of the front wheels 130. Beforepositioning rear wheels 128, it may be desirable to place them on aturntable or drive forward to unwind the tires. A straight edge may beplaced across the sidewall of the right side tire and in line with thevehicle's frame. The distance from the straight edge to the frame at thefront of the tire and the rear of the tire can then be measured. Thesemeasurements may need to take into account toe in of the tires. Forexample, for a typical vehicle 110 having one set of rear wheels 128,the tires may be toed in {fraction (1/16 )} of an inch. In this example,the distance from the straight edge at the front of the tire to theframe will be {fraction (1/16)} of an inch less than the distance fromthe straight edge at the rear of the tire to the frame. If themeasurements show that the rear wheels 128 are not in a straight aheadposition, the rear wheels 128 may be adjusted using a button located onthe vehicle near the rear wheels 128. In another embodiment, the rearwheels may be adjusted using a variety of devices such as the graphicaluser interface 146 or a handheld device (PDA or laptop) that isconnected to communication network 132 either wirelessly or using acable. After positioning the rear wheels 128 straight-ahead, controlsystem 112 recognizes the position of encoder 134 as the straight-aheadposition for rear wheels 128 in manner similar to that described abovein connection with the front wheels 130. The method of determining thestraight-ahead position of other sets of rear wheels may be done in asimilar manner to that described.

At step 197, the right and left stop positions of the front wheels 130may now be calibrated. Typically, this may be done by manually steeringthe front wheels 130 all the way to the right until the wheels stop andactivating the calibration button to notify the control system 112 thatthe front wheels 130 are at their right wheel stop position. The frontwheels 130 may then be manually steered all the way to the left untilthe wheels stop. Again the calibration button is depressed to notify thecontrol system 112 that the front wheels 130 are at the left stopposition. The control system 112 now knows the end points of the frontwheels 130. Again other methods may be used to calibrate the right andleft stop positions of the front wheels 130. For example, control system112 may be configured to automatically move front wheels 130 to theright and left stop positions. Control system 112 could sense that thefront wheels 130 have reached the stop position using a position sensoror pressure transducer measuring the increase in hydraulic pressure atthe stop positions.

At step 198, control system 112 enters a learn process where it learnsthe valve thresholds necessary to operate the cylinders. Because theweight of the vehicle may influence the valve thresholds, it isgenerally desirable to perform the learn process with the vehicle at itsnormal operating weight. The valve thresholds generally represent theminimum electrical signal required to turn the wheels. In a furtherembodiment, control system 110 may also compensate for the temperatureeffects of the hydraulic fluid. For example, the hydraulic fluid may becold and, thus, have a higher viscosity when vehicle 110 is started sothat the valve threshold calibrated at start up may not be inaccurateafter the vehicle 110 has been operating for while and the hydraulicfluid has heated up. One way to overcome this problem is to monitor thetemperature of the hydraulic fluid. Using the hydraulic fluidtemperature as an input, control system 112 can adjust the calibratedvalve threshold for an increases or decreases in temperature of thehydraulic fluid. Also, control system 112 may include a weight sensorthat could be used to likewise adjust the valve threshold as weight isadded or removed from vehicle 110.

In another embodiment, the encoders 134 may be enclosed withinprotective covers or enclosures in order to protect the encoders 134from damage (e.g., from rocks, shredded tires, road debris, or the tirefalling on the encoder during wheel installation). Each enclosure may befabricated to fit over one of the encoders 134 and is preferably strongenough to prevent damage to the encoder 134. The enclosure may beprovided with a sealing mechanism to permit the enclosure to be filledwith a moisture-repelling material such as grease. To this end, athreaded hole for a cord-grip style device to seal around the encoderwire along with a grease zerk to allow the cavity between the encoder134 and enclosure to be filled with the grease may be provided.

In another embodiment, and referring now to FIG. 56, an alignmenttrailer device may be provided comprising a one-axle trailer 193. Thetrailer 193 has an encoder 194 attached to a pivot point where a hitchball would typically be located on a conventional trailer. Attached tothe pivot point is a coupling (e.g., a square tube or similar piece)that is assembled into a receptacle on the vehicle 110. The encoder 194,which may be coupled to the interface module 114 a, is calibrated suchthat the encoder 194 is “zeroed” when the length of the tube isperpendicular to the axle of the trailer 193. If the vehicle 110 is offtracking, the encoder 193 no longer outputs a zero reading. The steeringcontrol system 112 monitors the encoder 194 and computes an averagereading. When the vehicle 110 makes a turn and the rear axles steer, anew set of center values will be used. Each center value change issmall. The net effect is that as the truck is being test driven, thevehicle 110 tracks straighter with each turn, and at the end of the testdrive the vehicle will track perfectly straight ahead. Such anarrangement may be used to reduce set-up time of the control system 112.

In another embodiment, the graphical user interface is configured suchthat portions of the screen become larger, perhaps even enlarging tofill the entire display 146. For example, if the vehicle 110 exceeds 38mph in the coordinated mode of operation, the top half of the display146 displays a forward rear lock indicator and the bottom half displaysthe rear lock indicator. The screen remains in this configuration for apredetermined period of time (e.g., between five and fifty seconds)seconds after the rear lock indicators indicate “LOCKED,” after whichtime the screen returns to normal. This assists the operator inascertaining whether the locks have locked. This arrangement would alsobe useful when speed is reduced below 38 mph. As another example, when anew mode is selected, the current mode and the previous mode portions ofthe display may become larger to make it easier for the operator toascertain the mode in which the vehicle 110 is operating. Also, theerror screen may be configured such that when reading codes, a menucomes up in connection with each error code that assists the operator introubleshooting the problem associated with a particular code. The errorscreen may also be configured to offer additional information, e.g., tohelp the operator move the vehicle to the side of the road.

It may also be noted that the vehicle 110 may be implemented as anelectric vehicle as described previously herein and/or be implemented toinclude the network-assisted monitoring, service and/or repair featuresdescribed previously herein. For example, when diagnostic codes aregenerated as discussed in connection with Table III, this informationmay be reported to an off-board monitoring computer and possibly used toorder replacement parts. The steering control features of the vehicle110 may also be combined with the features of other types of vehiclesdescribed herein, such as the fire truck, airport rescue fire fightingvehicle, military vehicle, multipurpose modular vehicle, snow blowervehicle, concrete placement vehicle, refuse vehicle, ambulance, and soon.

Throughout the specification, numerous advantages of preferredembodiments have been identified. It will be understood of course thatit is possible to employ the teachings herein so as to withoutnecessarily achieving the same advantages. Additionally, although manyfeatures have been described in the context of a vehicle control systemcomprising multiple modules connected by a network, it will beappreciated that such features could also be implemented in the contextof other hardware configurations. Further, although various figuresdepict a series of steps which are performed sequentially, the stepsshown in such figures generally need not be performed in any particularorder. For example, in practice, modular programming techniques are usedand therefore some of the steps may be performed essentiallysimultaneously. Additionally, some steps shown may be performedrepetitively with particular ones of the steps being performed morefrequently than others. Alternatively, it may be desirable in somesituations to perform steps in a different order than shown.

Many other changes and modifications may be made to the presentinvention without departing from the spirit thereof.

1. An electronic control system for a vehicle comprising: a plurality ofinput devices, the plurality of input devices including a first inputdevice that provides information pertaining to a steering angle of firstvehicle wheel; a plurality of output devices, the plurality of outputdevices including actuator capable of adjusting one or both of thesteering angle of the first vehicle wheel and a steering angle of asecond vehicle wheel; a communication network; and a plurality ofmicroprocessor based interface modules, the plurality of interfacemodules being interconnected to each other by way of the communicationnetwork, and the plurality of interface modules being coupled to theplurality of input devices to the plurality of output devices, theplurality of interface modules including one or more interface modulesthat is coupled to the first input device and to the actuator; whereinthe electronic control system is configured to control the steeringangle of one or both of the first and second vehicle wheels as afunction of the information from the first input device.
 2. Theelectronic control system of claim 1, wherein the information pertainingto the steering angle of the first vehicle wheel includes a steeringsignal.
 3. The electronic control system of claim 1, wherein theinformation pertaining to the steering angle of the first vehicle wheelis a digital signal.
 4. The electronic control system of claim 1,wherein the electronic control system is configured to detect errorsassociated with the electronic control system.
 5. The electronic controlsystem of claim 4, further comprising: a graphical user interfaceconfigured to display the detected errors; wherein the electroniccontrol system is configured to store and display a history of errorcodes.
 6. The electronic control system of claim 1, wherein: theactuator adjusts the steering angle of the second vehicle wheel; and theelectronic control system is configured to control the steering angle ofthe second vehicle wheel as a function of the information pertaining tothe steering angle of the first vehicle wheel.
 7. The electronic controlsystem of claim 6, wherein the electronic control system includes aplurality of modes for controlling the steering angle of the secondvehicle wheel as a function of the information pertaining to thesteering angle of the first vehicle wheel.
 8. The electronic controlsystem of claim 7, wherein the plurality of modes comprises: a firstmode in which the steering angle of the second vehicle wheel is fixed; asecond mode in which movement of the steering angle of the secondvehicle wheel is generally opposite to movement of the steering angle ofthe first vehicle wheel; and a third mode in which movement of thesteering angle of the second vehicle wheel is generally similar tomovement of the steering angle of the first vehicle wheel.
 9. Theelectronic control system of claim 7, further comprising a graphicaluser interface configured to display the past, present, and future modesof the electronic control system.
 10. The electronic control system ofclaim 7, wherein: the plurality of modes includes a first mode and asecond mode; and the electronic control system is configured to receiveinput to change from a first mode to a second mode, and, in response tothe input, the electronic control is configured to operate in the firstmode until one or both the first and second vehicle wheel travelsthrough a straight ahead position, at which time the electronic controlunit changes to the second mode.
 11. The electronic control system ofclaim 6, wherein the electronic control system includes a deadband of atleast about 5 degrees.
 12. The electronic control system of claim 6,wherein the electronic control system includes a deadband that varies asa function of the vehicle's speed.
 13. The electronic control system ofclaim 6, wherein the first input device is a sensor that measures thesteering angle of the first vehicle wheel.
 14. The electronic controlsystem of claim 13, wherein the sensor is an encoder.
 15. The electroniccontrol system of claim 14, wherein the information output by theencoder is converted to SAE J1939 protocol and communicated over thecommunication network to the plurality of interface modules.
 16. Theelectronic control system of claim 6, wherein the electronic controlsystem is configured to lock the second vehicle wheel in astraight-ahead position once the vehicle reaches a certain speed. 17.The electronic control system of claim 6, wherein: the first inputdevice provides information pertaining to a steering angle of a firstset of vehicle wheels; and the actuator is capable of adjusting asteering angle of a second set of vehicle wheels.
 18. The electroniccontrol system of claim 6, further comprising: a lock configured to lockthe steering angle of the second vehicle wheel; and a graphical userinterface configured to display the status of the lock.
 19. Theelectronic control system of claim 1, wherein the electronic controlsystem uses a locked position of the second vehicle wheel as acalibration pain for a straight ahead position of one or both the firstand second vehicle wheels.
 20. The electronic control system of claim 1,further comprising: a graphical user interface which includes arepresentation of the vehicle including an image of the vehicle'swheels; wherein the steering angle of the vehicle's wheels in the imagechanges as the steering angle of the vehicle's wheels changes.
 21. Theelectronic control system of claim 1, further comprising a graphicaluser interface configured to display instructions related to calibratingthe electronic control system.
 22. The electronic control system ofclaim 1, wherein the actuator is a hydraulic actuator.
 23. Theelectronic control system of claim 22, wherein the plurality of inputdevices includes a sensor that provides information pertaining to thestatus of a hydraulic filter.
 24. The electronic control system of claim22, wherein the plurality of input devices includes a sensor thatprovides information pertaining to the temperature of the hydraulicfluid.
 25. The electronic control system of claim 1, wherein theelectronic control system is configured to log data pertaining to thesteering angle of one or both of the first and second vehicle wheels.26. The electronic control system of claim 1, wherein the electroniccontrol system is configured to determine the minimum electrical signalrequired to control the steering angle of the first or second vehiclewheels.
 27. The electronic control system of claim 1, wherein astraight-ahead position of the first vehicle wheel can be any positionon the first input device.
 28. The electronic control system of claim 1,wherein the electronic control system uses a feedback control loop tocontrol the steering angle of one or both of the first and secondvehicle wheels.
 29. The electronic control system of claim 28, whereinthe feedback control loop is a proportional-integral-derivative controlloop.
 30. The electronic control system of claim 1, further comprising avehicle wheel alignment system.
 31. The electronic control system ofclaim 30, wherein the electronic control system receives input from thevehicle wheel alignment system and uses the input to determine thestraight ahead position of one or both of the first and second vehiclewheels.
 32. The electronic control system of claim 30, wherein theelectronic control system receives input from the vehicle wheelalignment system and uses the input to align one or both of the firstand second vehicle wheels.
 33. The electronic control system of claim 1,wherein each of the plurality of interface modules includes an I/Ostatus table, the I/O status table including I/O status information forthe plurality of input devices and the plurality of output devices. 34.The electronic control system of claim 33, wherein each of the pluralityof interface modules broadcasts I/O status information to each of theother interface modules, the I/O status information pertaining to 110states of the respective input and output devices coupled to theinterface modules.
 35. The electronic control system of claim 34,further comprising a graphical user interface configured to display theI/O states of the respective input and output devices.
 36. Theelectronic control system of claim 35; wherein the plurality ofinterface modules, the plurality of input devices, and the plurality ofoutput devices are distributed throughout the vehicle.
 37. Theelectronic control system of claim 36, further comprising: a powersource; and a power transmission link; wherein the plurality ofinterface modules are coupled to the power source by way of the powertransmission link; and wherein each respective interface module islocally disposed with respect to the respective input and output devicesto which the respective interface module is coupled so as to permitdistributed data collection from the plurality of input devices anddistributed power distribution to the plurality of output devices. 38.An electronic control system for a vehicle comprising: a plurality ofinput devices, the plurality of input devices including a sensor thatprovides information pertaining to a steering angle of a first vehiclewheel; a plurality of output devices, the plurality of output devicesincluding an actuator capable of adjusting a steering angle of a secondvehicle wheel; a communication network; and a plurality ofmicroprocessor based interface modules, the plurality of interfacemodules being interconnected to each other by way of the communicationnetwork, and the plurality of interface modules being coupled to theplurality of input devices an to the plurality of output devices, theplurality of interface modules including one or more interface modulesthat is coupled to the sensor and to the actuator; wherein theelectronic control system controls the steering angle of the secondvehicle wheel as a function of the steering angle of the first vehiclewheel.
 39. An electronic control system for a vehicle comprising: asensor that provides digital signals pertaining to a steering angle of afirst vehicle wheel; and an actuator capable of adjusting one or both ofthe steering angle of the first vehicle wheel or a steering angle of asecond vehicle wheel; wherein the electronic control system receives thedigital signals from the sensor and controls the steering angle of oneor both of the first and second vehicle wheels.
 40. A vehicle having anelectronic control system comprising: a first set of vehicle wheelshaving a first steering angle; and a second set of vehicle wheels havinga second steering angle; wherein the electronic control system includesa plurality of modes for controlling the second steering angle as afunction of the first steering angle, the plurality of modes including afirst mode and a second mode; wherein the electronic control system isconfigured to receive input to change from a first mode to a secondmode, and, in response to the input, the electronic control unit isconfigured to operate in the first mode until at least one of the setsof vehicle wheels travels through a straight-ahead position at whichtime the electronic control unit changes to the second mode.
 41. Avehicle having an electronic control system comprising: a first set ofvehicle wheels having a first steering angle; a second set of vehiclewheels having a second steering angle; and a lock configured to maintainthe second set of vehicle wheels in a lock position; wherein theelectronic control system controls the second steering angle as afunction of the first steering angle; and wherein the locked position ofthe second set of vehicle wheels is input to the electronic controlsystem as a calibration point for a straight-ahead position oft secondset of vehicle wheels.
 42. A vehicle having an electronic control systemcomprising: a first set of vehicle wheels having a first steering angle;and a second set of vehicle wheels having a second steering angle;wherein the electronic control system controls one or both of the firstand second steering angles; and wherein the electronic control system isconfigured to log the steering angle of one or both of the first andsecond set of vehicle wheels.
 43. An electronic control system for avehicle comprising: a sensor that provides information relating to asteering angle of a first set of vehicle wheels; an actuator capable ofadjusting a steering angle of second set of vehicle wheels; and agraphical user interface; wherein the electronic control system controlsthe steering angle of the second set of vehicle wheels as a function ofthe steering angle of the first set of vehicle wheels; and wherein thegraphical user interface displays calibration instructions forcalibrating the straight-ahead position of the first and second sets ofvehicle wheels.
 44. A system comprising: a vehicle which includes afirst set of vehicle wheels having a first steering angle; a second setof vehicle wheels having a second steering angle; and an electroniccontrol system; wherein the electronic control system controls thesecond steering angle as a function of the first steering angle; avehicle wheel alignment system; wherein the electronic control systemreceives input from the vehicle wheel alignment system and uses theinput to determine the straight-ahead position of the second set ofvehicle wheels.
 45. A vehicle having an electronic control systemcomprising: a first set of vehicle wheels having a first steering angle;a second set of vehicle wheels having a second steering angle; agraphical user interface which includes a representation of the vehicleincluding an image of the first and second sets of vehicle wheels;wherein the first and second steering angles in the image change as thefirst and second steering angles of the first and second sets of vehiclewheels change.
 46. The electronic control system of claim 38, whereinthe sensor is a digital sensor.
 47. The electronic control system ofclaim 38, comprising: a graphical user interface configured to displayerrors associated with th electronic control system; wherein theelectronic control system is configured to store and display history ofthe errors.
 48. The electronic control system of claim 38, wherein theelectronic control system includes a plurality of modes for controllingthe steering angle of the second vehicle wheel as a function of thesteering angle of the first vehicle wheel.
 49. The electronic controlsystem of claim 48, wherein the plurality of modes comprises: a firstmode in which the steering angle of the second vehicle wheel is fixed; asecond mode where the steering angle of the second vehicle wheel movesin the opposite direction as the steering angle of the first vehiclewheel; and a third mode where the steering angle of the second vehiclewheel moves in the same direction as the steering angle of the firstvehicle wheel.
 50. The electronic control system of claim 38, comprisinga graphical user interface which includes a representation of thevehicle including an image of th vehicle's wheels, and wherein thesteering angle of the vehicle's wheels in the image changes as thesteering angle of the vehicle's wheels changes.
 51. The electroniccontrol system of claim 38, wherein each of th plurality of interfacemodules includes an I/O status table, the I/O status table including I/Ostatus information for the plurality of input devices and the pluralityof output device , and wherein each of the plurality of interfacemodules broadcasts I/O status information to each of the other interfacemodules, the I/O status information pertaining to the states oftrespective input and output devices coupled to the interface modules.52. The electronic control system of claim 39, wherein the actuatoradjusts the steering angle of the second vehicle wheel, and theelectronic control system uses the digital signals to control thesteering angle of the second vehicle wheel as a function of the firstvehicle wheel.